please excuse my extreme ignorance on the issue but i'd like to find out more about what exactly SRS is and if it's possible to apply it to 5.0 or Lt/Rt mixes that then get bounced to stereo and encoded at 96 kbps for playback on 5.1 computer speaker systems (think creative or altec lansing).

SRS is like saying Dolby. Is the name of the company.
Which has a set of audio-related technologies (like Dolby) that can be applied from 2-ch to 6-ch audio and might involve or not a series of other separated technologies.
Two particular ones are:
TruSurround XT: it´s used for 6ch-to-2ch downmixing. It includes SRS Dialog Clarity and TruBass.
Circle Surround I and II: it downmixes 6.1ch to 2ch matrix encoded (CS) or upmixes 2ch to 6.1ch (CS II). Circle Surround II is designed to upmix anything from 2ch. It includes SRS Dialog Clarity and TruBass.

The thing is that if you don´t feed the encoder with enough bitrate, the spatial surround info might get destroyed in the process, and that would make the whole process pointless.

Cheers.