Any texture that has a horizontal and vertical size that is a power of 2 is fine. 800*600 is not a power of 2.

Noel R. Cower Portfolio Athlon 64 3000+, 1GB RAM, 400GB HDD, Radeon X800 XT Onboard Realtek 7.1 Audio, WinXP Home SP2, Slackware 10.0