In the past, when I've talked about introducing you to Linux, I've backed off on one thing that, for those of you who read here, would be of particular interest: the RAM requirements of SL and those of a Linux Live CD are such that I didn't think they'd work and play well with each other, and so I've hesitated to suggest it.
Last night I tried out the Sabayon Linux 3.5 Live DVD. I was happy to see it come up with the proprietary nVidia driver (and that the more recent version that, as far as I can tell, fixes the spot problem!)... but I was astonished to see the familiar turquoise eye-in-hand icon, labeled "Second Life". I clicked it... and there it was. I signed on, and it was just like always (well, not quite, since I normally run the RC client, and this was the official client). I checked the frames/second rating... and it was flying, in the higher fifties! Admittedly, I didn't have the knobs all twisted to max, and the window size was smaller (in pixel dimensions) than I usually run, but even so...
Another caveat: this was done with a 2.8 GHz dual core Athlon 64 system with 4 GB of RAM, so your mileage may vary, but OTOH that's not all that outrageous a setup these days.
So... I no longer hesitate to suggest that you try Second Life with a Linux Live CD. OK, DVD... but get the Sabayon Linux 3.5 Live DVD and give it a try. I think you'll be pleasantly surprised; I certainly was.