XP is very much better behaved than the 95/98/ME range. I'd be surprised if you had any serious problems.
I would start with the Internet connection, and get that working - because if there are any more drivers needed for the other peripherals, it's quite likely XP will go onto the Net and find them for you.
Do them one at a time, and you may be pleasantly surprised. USB stuff, in particular, is well behaved. Just read the instructions carefully for each item, to see if for XP you should just "plug and go", or run the Install routine before you plug it in.
For transferring files - if you have a router, with a LAN connection for the old and for the new machine, that's the way to go. I copied across many years' worth of stuff to my new machine a couple of months ago, via the LAN, and it was scarily fast.