Wow, G41D3C is pretty darn old. This point it's best for you to do quite a big upgrade or pretty much a new computer if you want to play at decent settings.
Most of the new graphics cards will be heavily bottlenecked by super old technology.
The bottleneck won't be so big if your CPU is from the LGA 775 chipset is really decent like a Core 2 Quad. But that's still not the best solution.
Linus from NCIX has a video where he'll explain bottlenecks.
I may be wrong though, I'm no expert. But hope this advice helps.