Spent most of yesterday night and a good chunk of today getting the wife's dad's new computer up and running. Decided to go with an HP Pavillion d4100 with a dual core AMD 64. Spent an hour or so disassembling his two old computers and moving the hard drives and DVD burner into the new one. Then the rest of the time was spent online downloading about 60 MB or so of software and security updates. Over dial-up. With a modem that kept resetting itself every few minutes until I could get some new drivers downloaded and installed. That was the painful part. The rest of it went fairly smoothly and uneventfully fortunately.
I'm really liking this HP Pavillion we got him. It's a bit of a monster case, but has plenty of expansion room with 4 5.25" bays, 2 external 3.5" bays and 3 internal 3.5" bays. Tons of room for stuff. Of course filling them all requires an additional IDE card (2 come on the motherboard) or other kind of internal interface. The case is nice and roomy inside, and all the components are easy to get to without having to contort your hands or anything.
About the only thing I'm not pleased with is the stock fan that comes with the CPU cooling system. It's a variable speed system, so you can hear it whir up and down as the CPU temperature changes. But when it spins up to full speed, boy does it make a racket. It's louder than both the power supply and main exhaust fan. I don't expect the dad-in-law to push the system hard enough that it's much of a bother to him, but if it was my system, the stock fan and cooler would be the first thing to go.
I think he'll be pleased with the new system. It's much zippier than the old one, and hopefully it stays that way (as long as he keeps from installing too much junk on it like the old one).