I just found out some great settings for the aliasing levels in XSI:
Sampling:
Min: 0
Max: 3
Filtering:
Type: Lanczos
Size X: 4
Size Y: 4
This method provides great renderingspeed while still having very nice edges and crispy textures. When using gaussian or box filtering you have to turn up the aliasing levels a lot to get the same result.
Hope you find this tips useful.