reformatting hd

I have an older Gaterway 450 mhz pentium III w/ 20 gb hd. I am running xp pro. Mt q is can I reformat only a corrupt partition? I have an image using acronis on a separate partition. I wolud like to reinstall a clean coppy of xp but would like to be able to retrieve info that is saved on the partition with the image. I have a corrupt copy of xp and a clean copy also but the performance seems to suffer. Is it possible to delete the corrupt copy w/out affecting the good copy? or would it be best to start from scratch?