nVidia GTX 750ti - the most powerful, supremely overkill graphics card for retro games, has working drivers for Windows XP SP3.
Windows XP should have plenty of drivers for Ivy Bridge (your CPU generation), and the system will be way overboard for retro gaming. Just keep in mind the 4GB memory address limitation of 32-bit OSes like Windows XP (Yes, there's a 64-bit version of Windows XP Pro, but finding drivers for that is a nightmare). The 750ti comes with 2GB of video memory, so you'll only really be able to have 2GB of RAM installed in your system and working. Everything else will effectively be ignored. You can install more RAM than that (to get dual-channel mode working), but Windows XP won't be able to see or use more than it can handle.
Besides, my old WinXP gaming laptop only has 2GB and that's more than enough for XP to be happy. And it's pushing a 7800GTX card with only 256MB of memory to a 1920x1200 display. And that only uses a single-core Pentium M @2.1GHz, no Hyper-Threading at all. Will XP be able to use more than 1 core? Sure. It's based off of the NT kernel, after all, so it plays nicely with 2-core and 4-core setups. I've just never used a multi-core CPU with XP before. I never needed to. Dual-core CPUs always meant Windows Vista or Windows 7 to me, usually with 4GB of RAM or more.