I had three Dell Intel's and an off-brand AMD. The AMD melted exactly two weeks ago. I now have four Dell's. The AMD was only two years old. One of the Dells has been running 24 hours a day for five years (the BJStats server.) The melt-down has been extremely inconvenient. I just got back my old e-mails and orders files an hour ago and will be reconfiguring for another week.

Having said that, the AMD is much faster for sims. But, is doesn't have hyper-threading. HT is wonderful if you run long intensive compute bound jobs (like sims) and also wish to use the PC for other tasks at the same time.

On cost, Dell is amazingly cheap, particularly if you buy a refurbished unit. (Although that may be US only.) I just bought a 3.0 GHz Prescott with SATA drive, PCI Express video card and half a gig of DDR2 memory for $713. Free shipping no tax. Very well built with an enormous heat-sink, quiet fans and a chassis that opens like a sandwich for easy maintenance. No screws for the case or the cards. Lift a plastic retainer and all of the cards can be pulled out. On the minus side, no support for my old EIDE disk or tape drive.

Of course this is just one person's experience.