Upgrading from NVidia GeForce 6100

Hello! I'm looking to upgrade from my NVidia GeForce 6100 + nForce 405. I'm pretty sure it's installed as an onboard chip, so I need to buy a card and install it. I'm looking for which card would be best (6600 GT) or one of the newer ones. I know how to install it, I'm just looking for what model would be best.

Here are the specs, and I have one PCI slot and one PCI-e open. I'm waiting until a later date to upgrade my RAM (as what I want to do doesn't require much more).

System Information report written at: 08/29/10 04:28:30
System Name: GTARK
OS Name: Microsoft Windows XP Home Edition
Version: 5.1.2600 Service Pack 3 Build 2600
System Manufacturer: Gateway
System Model: W3644
System Type: X86-based PC
Processor: x86 Family 15 Model 127 Stepping 1 AuthenticAMD ~2109 Mhz
BIOS Version/Date: Phoenix Technologies, LTD 6.00 PG, 11/10/2007
SMBIOS Version: 2.4
Total Physical Memory: 1,024.00 MB
Available Physical Memory: 152.43 MB
Total Virtual Memory: 2.00 GB
Available Virtual Memory: 1.96 GB
300 watt power supply

Thanks so much to anyone who can help me out.

well if you are running only a 300w power supply then you'll need a card that is powered by the expansion slot itself, and not requiring any external power as I doubt that power supply even has the modern 6-pin PCI Express power connection used on most cards today.

I would suggest avoiding all the older cards because they are..well..older, but also because newer cards offer more performance, with lower power consumption. So you win all around. So your best offering would probably be something such as the HD 5670 from ATI, which can be found for about $80 online, that model above is only $65 with rebate.

But according to the specs sheets, your system is equipped with an AMD Sempron LE-1200 processor which may hold you back in some games or applications. I am not sure if your system will allow you to upgrade your processor or not, but odds are it will take most AM2 processors without any fuss, but AM2+ chips may cause some trouble. I'd suggest looking into that and seeing if there is a bios update or any supported upgrades you can do to your CPU as a 2.1ghz single core chip is just a bit dated.

Thank you very much. I understand what you're saying and that's a lifesaver on Tech boards!

I'm looking into any bios updates as soon as possible, definitely. I've been noticing a decent lag in most of my programs since I upgraded to XP service pack 3 a few months ago.

Again, thank you very much. Upgrading my psu was going to be a massive pain right now, and not having to do it is just wonderful. It does say on the site that a 400w is recommended, but since it doesn't require a direct plug in to the psu, I don't really see why I need another one. I honestly don't play a massive amount of games on this computer- I mostly play online ones or puzzle games and The Sims 2 on my computer. ^^