I only have "out of texture memory" problem with firestorm, not with actual Second Life Viewer. I have ATI HD 4670, Win XP 32 Bit, Intel Dual Core CPU, latest DirectX 9c (:-?), newest drivers. It is maybe something wrong with cache management in programme code of firestorm .
Second Life Viewer is great. It hasn't so detailed Radar like Firestorm and they see you when you cam at them . lol. I use it for hours without crash. When I use Firestorm I crash after a few minutes.