Neither board is "better" in a sense....it's just what you need. The CUSL2-C should be fine for what you need.
Differences as compared to the CUSL2: CUSL2-C has no onboard i752 video, a standard AGP4x slot instead of AGP Pro, 1 CNR slot instead of 2, 4 USB ports instead of 7, no support for PPGA Celerons.
Other than that they are exactly the same...they even use the same PCB. There is no difference in performance.
I think that most of the differences above will not make a material difference to you, I think the CUSL2-C will be most suitable, given price.