Gettin' Tanked!

Ya'll, I got a new computer and after logging in today, I feel like I'm in Second Life for the first time again. With my Apple Macbook, I was stuck on low settings; I was crippled. But now, I can see water reflections, grass, and even clouds! There's only one problem, I can't use shadows on the official SL viewer or on Kirstens. Every time I check off "lighting and shadows", I just crash. My graphics card is a Gigabyte Nvidia Geforce GTX 460, so it should be able to handle it, right?

Anyone have any advice?

Picture 1:

Shirt: INDI Designs - Leighton Part 5 (5L)

Cargo Shorts :INDI Designs- Leighton Part 6 (5L)

Picture 2:

Tank: *FAC* - Get Stupid Green (0L)

Picture 3:

Tank: *FAC*- Light My Candle (0L)

Picture 4:

Tank: *FAC* - Maya (0L)

Picture 5:

Tank: Upperman/SE - SE Red Tank (Group Gift)

Picture 6:

Cargo Shorts :INDI Designs- Leighton Part 2 (5L)

Tank: *FAC*- Get Stupid (0L)

Picture 7:

Tank: *FAC* - Run For Cover (0L)