Until the first Vista service pack comes out at least, if you have choice, stick with XP, service pack 2.
2 Processor. Single, Core 2, Quad? What speed?
If its a portable and if you are into to any type of strong processing, go duo, and I would go Pentium Duos. If a laptop, then use the mobile versions, up to 2 ghz or a little more. I personally like the duo 3 ghz in my XPS 600.
3. Hard drive. Size? Two on board or just one? Portable back up?
I'd use a RAID configuration giving 320 Gig first line, and 320 Gig backup.
4. Graphics Card? I'm more of a Civilization-type/Strategy gamer than anything else. I don't need bleeding edge graphics but would like room for growth.
I'd make sure, if its a desktop that you had at least two PCI-E 16 slots so you can SLI if you ever need to. I personally like the NVidia cards, 7900 or higher.
5. Networking. Probably will use the new machine as the hub of network and use the old one as a kids machine. I'm inclined to worry about this later, so all I really want are expansion slots and (I'm guessing) some kind of network card.
I'd stay wired as opposed to being wirelss and use a good 10/110 card and a decent 10/100 hub.
6. Monitor. The 19" flat panel seems like a good trade between cost and screen size. Thoughts?
I'd get a 20" or 22" wide screen flat panel. That's what I sue on my XPS and it's great and reasonable price.
7. All in one. HP is offering All-in-one printer/copier/scanner/fax machines for $100-$200. Does anyone have any notable experiences with these?
If you are going to have a network, get an HP networkable color all in one, either inkjet or laserjet. I have four compuers networked in what my kids call the "control room". Mom, Dad, two sons. Lots of gaming, lots of surfing, lots of music and movies. We use the HP Photosmart D7260 and REALLY like it. It';'s a network, phot, all in one.
8. Data transfer? HP pushes a Belkin transfer cable. Is this anything more than a USB cable? Or should I just set up a network and deal with data transfer that way?
I always take care of this myself over the network.
Great. Thanks for the advice.