Sadly I'm getting the same problem and it's REALLY bugging me!
I played Roller Derby in SL and NEVER had any problems with graphics on my current system Seems that since the introduction of SSB and updates/upgrades to the available viewers I can't go anywhere remotely busy because I know that within 5 mins I get the 'Textures disregarded due to insufficient memory #' then crash.
System info:
Win XP home SP2
4GB RAM
MSI GTX460 with 1GB
Core i5 760 @2.8GHz
While it's not the fastest around these days it should be more than enough to handle SL without having to lower my graphics settings etc.
I've tried the LL viewer and Exodus and get the same error.
Have also tried the suggestions on the FS support pages, lowered my texture cache, cleared the cache, disabled VBO/http textures and just about everything else, all without any joy.
They suggested that it's an XP issue but looking at everything that's been written here it doesn't seem the case.
For the time being I've gone back to FS 4.3. and so far this has been running on ultra graphics without problem.
I really hope that someone comes up with a fix for this soon because I do like FS 4.4.2 even though I've seen more of the login screen than anything else