Need to replace 8600 GT

Hi all,
I need your help. I have a Dell Inspiron 530 that is not quite two years old, here are my specs:

Vista 32-bit
Intel core 2 duo E6550 2.33ghz
3gb RAM
Samsung 22" 2220wm (1680 x 1050 max)
300w PSU

I have a Geforce 8600 GT 256mb, that stopped working last week. I need a replacement video card, I want to stick with nvidia if possible I think it works better with the game I play (UnrealTournament 3, no time for anything else).

I am pretty much a noob when it comes to opening up the case and replacing anything. I think I can handle swapping the video card, but I am intimidated about replacing the power supply.

So my question is what is the best nvidia card that will work with my pc? Been looking at the 9600 GT but not sure if my PSU can handle it.

Also any tips, advice, encouragement if I go the route of replacing the power supply? I'm really hoping for somebody here to tell me replacing the PSU is no big deal, cause I would love to go with a 9800 GT or thereabouts.

I've been looking at these combo deals:

http://www.newegg.com/Product/Comb [...] mbo.245397
http://www.newegg.com/Product/Comb [...] mbo.245393
http://www.newegg.com/Product/Comb [...] mbo.245392
http://www.newegg.com/Product/Comb [...] mbo.244326

But I have no clue if they'll work in my pc or not. Are PSU sizes and the way they mount all standard?

Anyway any help would be greatly appreciated.
Thanks!

if really have the money then get antec + 9800GTX+ combo

If you look at the "GTS 250" its infact the 9800GTX+ but renamed to GTS 250 and its slightly more overclocked then the original.

Now in order to power such a card, you will need at least 500W PSU. I would reccommend a OCZ, they tend to be the cheapest and make VERY good PSU's.

Belive me, switching the PSU around is easy peasy. The only main one you need to unplug/replug is the motherboard pin connector (the bigest one that connects directly to the motherboard.) The rest anyone can do blind folded, you know... Hard Drive, CD Drive etc etc all use the same connector.

Seriously, give it a shot! Nothing could go wrong.

Edit: To get the most out of your gaming I would suggest downgrading to Windows XP. I used to be on Vista and damn, 15-20% of the GPU and CPU where being used up just to juice Vista.

Wow, having Vista on a Pentium 4 is bad enough Belive me, XP only needs 256MB of ram to operate, Vista needs 1GB. See the difference? Belive me, I would suggest having 3GB of ram to get the MAX out of your CPU when upgrading to Windows 7. This way, 1GB is used for the OS, and the other 2GB for you own needs.

I would still stick with XP though, add an extra gig of ram in there from ebay for like $10 and walla!

Still useing Vista with 1GB Ram and a Pentium 4? Seriously, downgrade to XP and add an extra gig of ram to make it 2GB.

Also, having a graphics card run on a 300W will only show its problems later on down the road when the PSU can't take it anymore. It really depends on what 300W you have. If its some generic crap, I would start to get worried.