I recently thought my CPU had fried so I bought a 939 4200+ dual core 64 it's a 2.2mhz. I had a 3500+ AMD 64 that was also at 2.2mhz. I now realize that the 3500+ is still good and that the issue was my power supply. I wound up getting Vista along with a new motherboard(I'm keeping those) but the 4200 dual core cost me $70 and I can send it back for a full refund. Since both processors are at 2.2mhz should I just send back the 4200. From my recall when I ran the Vista beta last year my 3500+ was just as fast but I've also recently heard that you need Vista Ultimate to run 2 core's. If I'm get nothing out of the 4200 AMD 64 then I might as well get my $70 back but if I'm getting better multi threading(doesn't seem like it) then I'll keep it. I have Vista Home Premium does it run dual core or am I screwed since its OEM and I can't return it, I'd got Ultimate if I knew I had to have it to run dual core. Anyway 3500+ at 2.2mhz and get my $70 or stay with the 4200+ at 2.2mhz.