Help getting Vista to recognize my old Hard Drive

Hi everyone,

Pls excuse in advance if this question is dumb and been answered elsewhere. My Win Xp crashed and I bought Vista since the XP CD was scratched. I formatted my 100 Gig IDE drive to hold my Vista OS and tried to keep my 500 Gig SATA II Western Dig. HD with my data intact. Unfortunately Vista will not recognize that the 500 gig drive data and tells me to format the drive. Does anyone know what I am doing wrong or whether I have no option but to reformat the WD drive. I am running a Core 2 Duo with 2 gigs RAM so it is not a hardware issue in terms of capability.

Thanks

Centu_rion