If money buys happiness, then some potentially vulnerable House incumbents probably are feeling pretty good right now.

Freshman Rep. Kirsten Gillibrand (D-N.Y.), for example, has 1,632,000 reasons to smile: That was the size of her campaign war chest at the end of September, following another stellar quarter of fundraising in which she collected $631,000, according to Federal Election Commission reports released earlier this week.

Also feeling good: Rep. Mark Kirk (R-Ill.), who was sitting on more than $1.5 million as of Sept. 30 and had outraised the combined intake of the two highly touted Democrats seeking to oust him, and a prime Republican target, freshman Rep. Tim Mahoney (D-Fla.). Despite being called a fluke by Republicans for winning a seat last fall that had been held by scandal-plagued Rep. Mark Foley (R), Mahoney took in more than the combined total of all three of the Republicans vying to take him on from July 1 to Sept. 30, and finished the period with more than $1.1 million on hand.

But just as the latest reports brought good news for some shaky incumbents, they probably added to the woes of others.

Rep. Barbara Cubin (R-Wyo.), who limped to re-election by 1,000 votes last year despite the heavy Republican lean of her state, raised just $11,000 in the three-month period and finished September with only $9,000 in the bank. Her fundraising performance does nothing to quell rumors that the seven-term Congresswoman plans to retire next year (a development that many national Republican operatives are secretly hoping for).

Rep. Jean Schmidt (R-Ohio), who has also struggled in a conservative suburban Cincinnati district, banked less than any of the three candidates — two Democrats and one Republican — who are trying to defeat her next year. Physician Victoria Wulsin, the Democratic nominee in 2006 who is seeking the nomination again this cycle, finished the quarter with $343,000 on hand — more than three times Schmidt’s total.

Scandal-tinged Rep. John Doolittle (R-Calif.) did nothing to ease Republicans’ fears about his grip on his Sacramento-area district by raising just $61,000 and banking $38,000. Charlie Brown, the Democrat who almost defeated him last year and is trying again, raised $215,000 and had $383,000 cash on hand. Equally significant, other Republicans are coming out of the woodwork to challenge Doolittle, though their fundraising is just getting off the ground.

Money will hardly be the only determining factor in the outcome of the most competitive House races next year. But the off-year fundraising totals help shape the contests early on and offer key clues to the candidates’ strengths and weaknesses.

While Gillibrand has been a phenomenal fundraiser from the minute she launched her candidacy in 2005, she benefited from the myriad problems of her opponent last year — then-Rep. John Sweeney (R-N.Y.) — and her re-election is by no means assured.

The leading Republican candidate is Sandy Treadwell, a former New York secretary of state and state GOP chairman who is personally wealthy. He raised $482,000 in the third quarter — $313,000 from his own pocket — and banked an impressive $637,000. That’s still almost $1 million less than Gillibrand’s cash on hand, however.

Other potentially vulnerable incumbents seem to have lucked out so far. In Ohio’s conservative 18th district, freshman Rep. Zack Space (D) reported a respectable $592,000 on hand after raising $275,000 from July to September. But while his seat is a major Republican target, the three GOP contenders raised just $88,000 collectively and banked a combined $110,000.

The same scenario is true in Minnesota’s 1st district, where Republicans hope to recapture the seat that now-Rep. Tim Walz (D) grabbed from then-Rep. Gil Gutknecht (R) in the previous cycle. Although two state legislators are among the four GOP candidates in the race, Walz, with $711,000 in the bank, has more than three times the cash on hand total of the four Republicans combined.

One of the Democrats’ shakiest freshmen, Rep. Carol Shea-Porter (D-N.H.), will never win any fundraising contests. She raised $151,000 in the third quarter and finished September with $377,000 in the bank.

But Shea-Porter benefits from a competitive Republican primary between the man she upset in November, ex-Rep. Jeb Bradley, and former New Hampshire Health Commissioner John Stephen. Stephen, in his first quarter as a candidate, outraised Bradley by $33,000, though Bradley had twice as much money on hand on Sept. 30.

The campaign finance reports showed that some challengers, regardless of the political skills they possess, probably will need to pick up the pace on the fundraising front. These include Fort Collins businesswoman Betsy Markey (D), who is running against Rep. Marilyn Musgrave (R-Colo.), businessman Steve Greenberg (R), who is taking on sophomore Rep. Melissa Bean (D-Ill.), and teacher Larry Kissell (D), who is seeking a rematch with Rep. Robin Hayes (R-N.C.). Kissell, who was outspent by more than 3-1 in his first try against the wealthy Congressman, now has a cash-on-hand deficit of 5-1.

Fundraising in some key House races seems very evenly matched.

In Washington’s 8th district, where Rep. Dave Reichert (R) and former Microsoft executive Darcy Burner (D) are headed for a rematch, Reichert raised $343,000 and Burner collected $307,000, but the challenger had a $30,000 lead in cash on hand.

In Missouri’s 6th district, both Rep. Sam Graves (R) and former Kansas City Mayor Kay Barnes (D) appear to be in mid-season form, with Graves raising $525,000 and banking $756,000 while Barnes took in $327,000 and banked $578,000.

The competitive open-seat race to replace Rep. Dennis Hastert (R-Ill.), the former Speaker, has three free-spending candidates, including state Sen. Chris Lauzen (R), dairy magnate Jim Oberweis (R) and scientist Bill Foster (D).

Other competitive open-seat races, including those to replace retiring Reps. Jim Ramstad (R-Minn.) and Ralph Regula (R-Ohio), are expected to be close on the financial front, but many of the leading contenders in those contests have only begun to raise money.