Hey! I got the same issue on my A853 Milestone (ghost touch, then some parts of the screen not working anymore). The problem is not necessarily on the digitizer. I suggest you to disassemble the phone and to verify the integrity of the flex cable. Mine was very used and I made the same mistake - I spent money on a new digitizer without checking the other component. So, first check that then buy the right part. Good luck! Best wishes from RO!
Device : Motorola Milestone A853 (defective digitizer ^^)
ROM : CyanogenMOD 7.2.0
CPU speed : 1200 Mhz (with 73vsel)