The Sempron 145 (am3 2.8ghz) + a radeon 5450 will be enough to cover win xp games until 2005?
Retro rig 1: Asus CUV4X, VIA c3 800, Voodoo Banshee (Diamond fusion) and SB32 ct3670.
Retro rig 2: Intel DX2 66, SB16 Ct1740 and Cirrus Logic VLB.
They may not run at the highest frame rates or settings but most should work okay.
Now for some blitting from the back buffer.
Almost anything modern will work for XP provided there is driver support but you are going to want to a dual core cpu and a halfway decent gpu for the later DX9 era titles.
On a far away planet reading your posts in the year 10,191.
For the sake of stability I highly anti-recommend any Radeon HDwhatever unless you have a PCI express slot to back it up on such an old motherboard. and even then you're probably stuck to the HD4850 at best. There's also additional visual quirks when you have this wasted DX10+class hardware trying to do older APIs it wasn't designed for (no dithering is a big one, but there's also some new depth artifacts)
When you have "for 2005" in mind, the Radeon X###/X1### family will be fine.
The Sempron would likely be fine (it's based on K10.5 and will handily outperform an Athlon 64 at the same clock). What I doubt is the possibility that an HD 5450 could keep up with an X1600, let alone the X1800 or the equivalent Nvidia cards of 2005...
