When you buy an HP laptop you buy an OEM copy of Vista too, and when buying computers from Dell I took getting the Windows OEM install disc for granted. But when I bought a new HP Pavilion dv5 1139tx I found it came with no CDs at all (and no up-front warning that it didn't come with CDs either).
If you want you can order a recovery disc, which comes with all of HP's shareware etc, but there's no option to get a fresh Vista installation disc. If you want to repartition your hard disc tough luck.
HP's customer support weren't helpful; a Indian sounding person called Chris, who annoyingly said "OME" instead of "OEM" for some reason, said in a very long-winded way and after several talks with his manager "no, we can't help, you have to buy /another/ copy of retail Vista to get an install disc, and to repartition you'll need to buy Partition Magic".
When you own a Vista OEM key these are the restrictions which apply: You can only use the key on one machine, no moving the CD key around, and you have to go the reseller for support/refunds. You are still allowed to use the normal Vista install CD, your key does cover the use of that software.
So the solution is to get an untouched OEM install disc from another source. It's not piracy if you have a valid key; you're downloading software which you already paid for but didn't recieve after all. It will recognize the edition of Vista which you paid for from the key you enter, and then all that's left is to hunt down the drivers. Since you're using your OEM license legally you can activate your copy of Vista OEM as normal without any cracks or patches.