MegaDrum MIDI drum trigger (link) is a fantastic DIY device that simply translates hits from the e-drum pads into MIDI notes and sends them over USB. This is all one needs to trigger the sounds when using VSTs.
Here is an outline of a solution that would be an alternative to standard e-drum modules.
Hardware requirements for Superior Drummer, for example, are: Pentium or Athlon 1.8GHz processor, minimum 1GB RAM. Today, this is met by any new PC that can be found on the market, including the Mini PC versions.
Input slot map:
1. hihat pedal
2. Kick (1 in MDM)
3. dual hihat input for bow/edge 2-3 in MDM)
4. Snare dual Head/rim (4-5 in MDM)
5. Tom 1 dual head/rim (6-7 in MDM)
6. Tom 2 dual head/rim (8-9 in MDM)
7. Tom 3 dual head/rim (10-11 in MDM)
8. Tom 4 dual head/rim (12-13 in MDM)
9. Crash dual head/rim (13-14 in MDM)
10. Crash 1 dual head/rim (14-15 in MDM)
11. Crash 2 dual head/rim (16-17 in MDM)
12. Crash 3 dual head/rim (18-19 in MDM)
13. Ride 1-1 dual Bow/Edge (20-21 in MDM)
14. Ride 1-2 dual NA/BELL (22-23 in MDM)
15. Flexi 1 dual head/rim (24-25 in MDM)
MegaDrum and AD2 map presets (link).