Just about anything will work. I'd recommend at minimum a 500mhz Pentium or equivalent, and 256 mb RAM. For a basic interface, try a USB one. They're easy to use and decent enough to start with. There are high end ones of course, but something like the M-Audio or Edirol pigtail connectors will probably work (since it sounds like your mic doesn't require phantom power).
I use a Fujitsu T70G, which is a 1ghz Pentium M with 1gb RAM and a VX Pocket 440 when I'm not multitracking with my 24 channel rig. That rig I use a larger desktop replacement type laptop (Fujitsu E7110 Pentium M 2.2ghz with 512mb RAM)...
Not sure if any of this info is all that helpful. Feel free to PM me if you want more detailed info and additional assistance.
Dirk