Fretted Synth Audio recently released Free Amp SE, a freeware "virtual guitar setup" for Windows.

Features:

• Choose from seven different amps types.
• Seven different eq's, all have there own controls for comparison.
• Six speakers, plus bypass, adjustable by the mic placement.
• Separate MIDI volume control, can be placed pre or post amp.
• Noise gate
• Tremolo, Triangle and square modulators.
• Two compressors, pre and post amp.
• Wah can operate by MIDI CC, plus has auto features.
• Drive pedal, with a choice of seven overdrive types.
• Chorus with added filter.
• Delay and Reverb.