CL 2 usually applies to PC2100 modules, but you are looking for PC2700 modules.
I presume your motherboard is a KT3 Ultra2-C (MS-6593). Compatible 1 GB modules (maximum 3 modules):
Crucial 1 Go DDR-SDRAM PC3200 CL3 - CT12864Z40B
Crucial 1 GB DDR-SDRAM PC2700 CL2.5 - CT12864Z335
Kingston ValueRAM 1 GB DDR-SDRAM PC2700 CL2.5 - KVR333X64C25/1G
Crucial don't provide clear specifications, but they should be low density like the Kingston module. It's up to you, but I'd buy modules that are guaranteed to work with that motherboard (or at least are low density, i.e., 16 chips).