acmegigbar.com has guitar amp VSTs available to download. They are primarily geared toward Metal and Rock. For a jazz tone I recommend
It gives my fender the warmest sound. It's simply incredible.
You will need a VST host or recording software that supports VST hosting.
Dont have either you say? That's ok. Go to ifoundasound.com and download liveprofessor. It is free as well. You can import your VSTs into live professor to run. As far as system reqirements, None are posted on the sites.
My best guess is 800 mhz to 1 GHz processing speed?
Most of the Guitar VSTs have no effects so... head over to vstplanet.com. Available there are reverb, delays compressors to sweeten your sound. nice heh?
CRUD! ALMOST! FORGOT! You may also need an ASIO driver. (Audio Stream Input Output) If your recording software does not have it. No problem. . . ASIO4ALL at asio4all.com will do the job for ya.
Just sharing the info -Scott