You need to make your Recovery Disks before wiping a Recovery Partition, or else order them from Dell if you ever need them. You can also clean reinstall Vista using any Vista retail installer for your version.
I remember the media-less Recovery Partition tutorial when Cereal Killer posted it up because it involved way more work than needs to be done since you can simply store a Windows 7 backup image in a Primary partition and reimage it from the Repair My Computer choice on Advanced Boot Tools menu accessed by tapping F8 at bootup.
If you don't have the 100mb System Reserved partition which places the Repair Console at F8, then you can boot the Repair CD or Windows 7 DVD this to me is a lot easier than having a Dual Boot menu every time you start up (which cannot be hidden as you may need it at any time) when you don't even have a Dual Boot.
To answer your question: You can replace the Vista Recovery partition by running the Recovery Disks, I believe, however it is not really needed now that it's gone since you can order the disks or use a Vista DVD if ever needed.
For recovery using Windows 7 system image, the best approach is always to store it externally (in case of HD failure) and when needed boot from the Repair CD, DVD Repair console, or F8 Advanced Boot Tools menu if you have 100mb SysReserved partition.
That said, I have a copy of my System image stored in a Primary partition on all 6 of my home computers. I have used it while traveling to reimage a laptop booting via the F8 key to Repair My Computer>Recover Using an Image. If there is enough RAM to load WinRE into memory then it can work, otherwise it wants the Repair Disk or DVD.
In order to make a Windows 7 recov partition which boots from the Fkey set up by manufacturer, the BIOS would have to be modified to mark active and then boot that partition. Backup Complete Computer - Create an Image Backup System Repair Disc - Create Repair CD - System Repair Disk