I doubt there would be "massive" issues. I run 3, NVS 295s with 512MB each... RAM available is 2.88GB from a 4G kit... but fully loaded, my rig uses <1GB RAM, so plenty of head room still. If he has 32-bit OS now, I'd suggest trying it out before concluding he must change to 64-bit OS... unless he just wants to change, of course. Also, I like the idea of the T3500 instead of the T3400. With the T3500, he could run 2, NVS 295 x16s and 2 NVS 295 x1s. If bought from eBay, should be able to do all 4 video cards for $350 or less, total.