"Can i connect xp drive as second drive"
Yes, but pc will boot into W7 and you won't be able to use any programs that are on the XP drive (it will just be another slave drive)
W7 cable to motherboard sata 0 and XP cable to sata 1
I have the same setup. When I want to boot into XP I swap the cables on back of harddrives (before I switch the pc on) and then the W7 harddrive is on Sata 0