For keyboards or strings I find it's hard to beat the Ketron SD2. Just to jam along with though I'd use the VSC DXi.
For sax I use the free sfz soundfont player from Calkwalk with a good soundfont.
For clean guitars I use sfz and an appropriate soundfont from a half dozen or so free ones. I'd use amplitube for amplification. Ususlly the BBClean preset.
For overdriven lead guitar I'd use sfz and a good sound font with a combination of FX from Camel Crusher, Killapluggies or PGM. For amplification I'd use Juicy77. Links provided in the Tips and Tricks entry for creating Hendrix style guitars.
For vocals I'd use the GComp2 compressor, the Detuna from killapluggies and 10 band EQ from PGM.
BiaB 2013 b366, RB 2013 b4, WinXP Pro SP3, Toshiba M70, 1.8GHz 2GB RAM 100GB HD. Focusrite Saffire 6 USB, Ketron SD2.BiaB Wiki