Chosing a low power VGA card for my Dell w/ 300W stock CPU

Hello,

I just ordered a Dell 570MT with an Athlon II X4 630, and 4 GB of DDR3 Ram. (I got it because a friend of mine works there and he let me use his EPP coupon for the quarter, so it was a good deal bundled w/monitor. Also I'm poor, cheap and not a hardware enthusiast  )

I will not be overclocking anything of course, and I just want a machine that can run games from the past 4-5 years at settings good enough to enjoy them, not to dazzle. A single 23" monitor will be running off the card.

Anyway, from this site and other sites I understand that despite the Dell specs claiming the power supply is 300W , it can almost certainly run these cards:

A) Galaxy 9800gt 512MB 98TFF6HXXEXZ (costs about $85 or so after rebate- probably the cheapest)

http://www.tigerdirect.com/applications/SearchTools/ite...

B) BFG 9800 gt 1GB BFGE981024GTGE (about $100-110 after rebate)

http://www.bfgtech.com/bfgr981024gtge.aspx

C) Galaxy 96GFF6HVDCXX GeForce 9600 GT 512MB

http://www.tigerdirect.com/applications/SearchTools/ite...

The galaxy 9800gt I listed is lower performance (less memory) than the BFG 9800 gt. The manufacturer suggests a 400w power supply minimum for it. The BFG 9800 gt is $20 more, but it has more memory, and the manufacturer suggests 350w, so it is higher performance, lower power consumption.

The Galaxy 9600 gt is about the same $ as the Galaxy 9800 gt, similar specs and benchmarks, but requires less power (350w). However, I see that it does not have exactly the same features as the galaxy 9800gt- for instance "PhysX". But it seems the board's "Quantum whatchamacallit" feature is pretty much just the "PhysX" feature marketed under an old name; not sure if any of that really matters much.

SO considering the machine I am working with and my cheapness, should I just go with the cheapest of these? Should I go for the least power consumption? Or are there even cheaper or better cards that will perform just as well on my machine? I might upgrade in the future, but if I do it would probably just be more RAM.

If I am possibly about to destroy my new machine, a warning would be appreciated as well.  

Sorry for the same old question once again- I didn't see a more up to date version of the "will this card run in my dell" thread within the several months or so, and figured that's a long time in hardware years. I hope this is not a redundant post.

Thanks in advance!