Not knowing the specs of your PC, it's hard to make the best suggestion.
Are these IDE drives or SATA? If IDE, then most motherboards come with two IDE ports, each supporting 2 drives. You could either use the two spots as you mentioned, or hook them up to the secondary IDE.
You could also use the existing connectors if the drives are SATA. Or are there spare SATA ports on your motherboard?
If any case, you'll probably want to do the clone from a diskette boot. PC Inspector creates this diskette. I don't know how DrvCloneXP works. You'll create this diskette prior to performing the drive swap out, if that is the route you take.
In any case, be sure you know what drive has the data, and which drive is to receive it. If you reverse the order, you'll clone over the wrong drive and lose your data. This is the one scenario which made me mention backing up important data in my prior post.