I recently installed the ati drivers, and acceleration is working fine, I can use my modelling programs and everything seems flawless. (tested wings3d, tuxracer)
When starting SecondLife 1.9.0 under wine it starts up as if its the first time running SL - each time -- It says "detecting hardware" -> "Missing directx9 or something" (click ok) -> "Can't Create OpenGL Context" <- the error might not be word for word but the jist of it was being unable to create the opengl window.
I uninstalled the version of wine that is in the ubuntu repository(12/xx/05 something), and found the wine apt repository, I installed the latest version from the wine repository it was marked as a version 0.9.10 (I think)
I'm also running SL under wine on my gentoo box at work, P4 2.4ghz GF4 4600 128 1.5gb ram (not that I play at work *grin*) it runs perfectly. I'm a bit confused as to why it didn't just work "out of the box" under ubuntu (i'm also new to ubuntu - testing it out for my g'ma so perhaps I've not configured something)
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i'd also like to note, that I do not own Windows XP nor do i have a windows box to get to. Wine, and the linux client are my only options for SL
p.s. Linden Lab rules 
- but um hurry up with that 1.9 release