For those that were like I was, having used Unrevoked3 to root 2.1, below is the Froyo update so you can then flash to 2.2, then accept the OTA currently out. (FPS fix)
Download the file as is, and copy it to the ROOT of your SD card
On your evo, hold down the DOWN volume button, then hold and press POWER, you will boot into the bootloader, from there choose Recovery, then Install update.zip, let it do it's thing, in a few minutes you will boot back to your regular screen, Froyo updated, but no root access. From here you can then apply the new OTA update, and you'll be fully updated, and can now use Unrevoked3.21 to re-gain root!! No data loss, simple!! For google reference, the Froyo update file was originally named:
OTA_Supersonic_3.26.651.6-1.47.651.1_releasem24cfnusi9dsrr6i.zip
I have already renamed it as it should be, the above is just for google search, so for those looking for a copy!! Thanks to everyone that helped with this request!!
Hotfile.com: One click file hosting: update.zip