Performance is pretty similar (usually the V3 edges out ahead), though image quality and compatibility is slightly better with the Voodoo3. Voodoo I (not a typo, I not II) is actually better for DOS-based Glide games, so that's probably a better fit for the S7 machine anyway. Going V2 SLI means that your AGP slot is free for something that's not only your 2D card, but also a good D3D/OGL card (Voodoo II would need a miniGL wrapper for pure OGL, and they tend to suck a bit), again potentially a Geforce 256 SDR/DDR. Personally I find that the Voodoo 3 3000 is a good match for the K6-III, saves the faffing with MiniGL wrappers, has good image quality (compared with both the Voodoo II and the Geforce/Geforce2), and immense compatibility with everything (software and hardware).