These are cheaper than you think. For example -> http://www.geeks.com/details.asp?invtid=ISU-8484G&cat=DVD
The acid test for your old drive after you cleaned the lens is to try to boot the restore or other bootable CD. If not, it's broken.
I have a Pavillion ZE4560 US laptop running Windows XP. The hard drive crashed and I need to replace it. Problem it does not read cd' but it will read dvd's. My recovery disks are all cd's. I have tried hooking to axternal dvd burner by firewire but it does not boot from it (also changed boot order). In set-up one option is to boot from a LAN. I have that available if you think it is a solution. Anyone have any ideas?