I'm sure there are a lot of people that this won't help at all, but hopefully it'll help someone. It's a list of pitfalls I had last night (re-install took 5 hours, rather than 90 mins):
Problem 1
I had problems with my SATA drive. In the previous install, I had an IDE drive, partitoned to C

windows) and D

everything else) with the SATA drive E

recorded TV/DVD rips) and my dvd drive was F:. All pretty standard.
Except upon booting from the install CD, it thought the partitions were labelled C:, E: and D: respectively. Alarms bells should ring
After formatting and copying the files, the installer asked for disc 2 "Windows XP Professional SP2 disk". After insert said cd I got an error message like:
"The installer requires the 'asm' files on the cd .... please insert disc 2"
No amount of cd swapping, or trying all the letters of the alphabet helped!
Solution 1
Completely disconnect the SATA drive. No need to remove it from the case, just disconnect the data
AND power cables. Start again.
Problem 2
Do not assume that windows will provide network ability for the onboard NIC.
I had a linux samba server waiting with all my drivers, backups etc etc, but couldn't talk to it, cause I couldn't talk to it.
Solution 2
Burn a cd/dvd with at least the chipset drivers.
Finally .....
Don't bother setting up Media Center before you have performed a windows update. For some reason the guide for Sky wasn't mapping correctly (all channels started from 1, rather than 101), and the IR blaster wasn't working.
Hope this helps someone (even if it's me the next time I re-install, because I've forgot it all

)