DON'T try to take one of the upgrades that is available by going to settings->system updates->HTC updates.
There are plenty of ROM's you can get on XDA that will upgrade your phone to gingerbread. If you've stuck with Froyo for this long, I will assume that you like a stock look and feel. If you want to be dull, you could download the stock, rooted rom on XDA here:
[ROM][STOCK][Rooted] 4.53.651.1 - Odexed & De-Odexed - xda-developers
Go with ODEX. It's faster, although less customizable, but if you want stock, they customization really doesn't matter.
For the record, I would STRONGLY recommend the latest version of MikG. It's rock solid, and has more bells and whistles than the plain old stock ROM. It is running Sense 2.1 rather than Sense 1.0, and it also has some built in Sense 3.0 features that are very nice. So it's like a hybrid of Sense 2.1 and 3.0. Here is the link for that (you may have to register for Mik's site to download, but it's worth it):
Download Links
When flashing any ROM, you need to make absolutely certain to make a nandroid backup (including your wimax keys) just in case anything would go wrong. I also use SMS Backup and Restore to back up my text messages so I don't lose them all.
Other than that, go into recovery, do a factory reset, wipe data, wipe cache, wipe dalvik cache. After that flash the zip file. You should probably also get a copy of Calkulin's Format All zip file and flash that prior to flashing the ROM.
http://www.google.com/url?q=http://www.mediafire.com/%3Fikylelx99c49133&sa=U&ei=8-yNTtPrHeatsAKH-fi7AQ&ved=0CBEQFjAA&usg=AFQjCNGS-CSWvWEhHlaauysN-2ie5U2pxQ
So in short,
1) make a nandroid backup
2) Wipe data/factory reset, wipe cache, wipe dalvik cache
3) Flash the Calkulin Format All zip file
4) Flash your ROM
5) Reboot and you're done!
Happy flashing!