Need help choosing between these 2 pc desktops.?

Get the second one. The difference in the speed of the processor is almost nothing. One thing you didn't mention is how much memory expansion both offer. The one thing that popped out at me is the free upgrade to Win 7 and trust me, you'll want out of Vista and into 7 as soon as you can because Vista is just a frightening memory hog. That's a nice perk. Really when you get down to it, it's not the processing speed that really makes or breaks a computer but the memory allocation. The other nice thing about the second one is that it has 2X the drive space of the other one which means that even if you stretch your memory, you'll have much more disk swap space to make up the difference. I'd definitely go for the second one if it were me and I've been buying and sometimes building computers since the IBM PC. Also don't forget, if you do any graphics at all then you should see whether either or both have a PCI-X expansion slot for graphics.