ok as for
PC: you are gonna have to look around to build it within 1k. I would suggest minimum Pentium 4 or Athlon 1800 for processor, if you can, two silent hard drive disks, could be Maxtor, Seagate within others....and a brand motherboard ( Asus, Soyo, Gigabyte, Epox) and at least 512 M of Ram. Other components are less critical, if I didn't leave any other core component behind....And use XP Pro as OS.
Soundcard:
Depending on the number of I/O's that you need. Within $550 you can get a Delta 1010 with 10 I/Os, don't remember how much the Q10 is and a Layla woud cost you a couple hundred more. This are not the only choices but are SOME of the best that popped out of my head.
This comes to $1500. but you would still need a mixer (preamps) for your routing, a good one, depending on how many channels you need, would cost from $500 to $1000. Brands: Mackie, Soundcraft, Allen and Heath within others....Maybe you need to save some more or sell something. This is just a rough description of choices. I am sure more questions arose so post them......