Why would he want an AMD???? P4 will be more than sufficient...even a celeron would be very capable for doing office tasks....
If there is one thing that you can applaud the P4 for it is office productivity and video editing....
What sort of budget do you have Clusoe???
If I were you I would head straight over to Dell....
www.dell.com...they offer good rebates for US customers and their computers are fantastic value and you would be hard pressed to build one for the same price...
From the questions you asked it seems like you are not too clued up on computers(hardware) I would steer you away from a self-build....
Basically any reasonable PC that you buy will be capable of doing the tasks that you specified as they aren't exactly computationaly intensive tasks...
Pentium4 and AMD64 will be best but you coupld always look out for AMD Athlon XP or even Intel Celeron... look for at least 512MB RAM.... more if you get a PC with integrated graphics....as the graphics will share the system memory....If you want to write DVD's you will need a DVD+/- RW...
Graphics and audio cards are always separate.....but you will be able to get them both integrated on the motherboard if you want to cut costs......
Hope this helps.....