If your system originally used XP then it's possible that the win7 install made changes to your mbr/boot loading that made it impossible for your recovery partition to boot if it's on the same disk as the win7 partition, although I'm not sure I could explain why that is.
It's been a very long time since I read about the difference in how mbr/booting is handled between XP and Vista and 7 (I'm not even sure that there's much of a difference between Vista and 7 in that respect) but there was a lot of information about it on the forums for a freeware program called EasyBCD which is a utility to fix/repair/change your booting settings from within a running windows install.
If you're certain the recovery partition still exists, this utility's forum may be exactly the place to find out how to use it to do a proper and legal restore.
lecture on deleting recovery partitions edit:
In the recent years of working with setting up PC's or reconfiguring them, particularly manufactured desktops/laptops/netbooks, I have learned a very important lesson when it comes to recovery partitions. Never remove the recovery partition unless you are absolutely certain you will keep it for yourself and never use the factory settings, forever and ever. I've had two situations where things were screwed up and the restore partition had been removed by me or a well intentioned person recovering the disk space. One of those times the solution was to pay $30 to HP for the S&H fee for their damn recovery disc because using the legit OEM license was a necessity and using a pirate install was only permissable to keep the computer operational until the factory restore disc was received. The other situation is a bit more minor but the result is being unable to resell a laptop with a genuine licensed operating system, which has a more significant effect on resale value when you have something that is otherwise "complete, with box and manual". This laptop had been packaged with two recovery DVD's in addition to having a recovery partition, and I lost one of the recovery DVD's, and it's the one with the OS on it. -.-
Disk space, removable media, and flash/ssd storage are so affordable now, I don't recommend deleting recovery partitions even if you have equivalent restoration media (unless you are certain you will own the product permanently and really want that 4-to-20gigs that badly) - my reasoning being that restoration media can be lost, or with laptops, perhaps a failure occurs during travels and you did not keep the media with you, or using a netbook and don't have the media nor the external disc drive.
Furthermore, in the past few years it's a lot more common for mainstream models not to be bundled with ready-made recovery media, instead having a utility that asks you to burn the discs yourself during the initial setup. It is a much easier process to restore from a partition than from multiple DVD's or CD's..
