I have a desire and my missus has a wildfire. I would consider the wildfire for £180 if you can live with the poor screen.
To be honest I dont think theres that much of a difference apart from the screen (which isnt that bad until you put one next to the desire). The Wildfire does most the stuff the desire can do and will also get Android 2.2!
Good
Powerful Android operating system
Wi-Fi and HSDPA connectivity
GPS
Address book merges your contacts and social-networking chums
Syncs photos with Facebook and Flickr
Useful app-sharing feature
Doesn't look cheap
FM radio
Multi-touch support
Inexpensive
Flash Lite so you can see pretty much the whole Web
Bad
Low-resolution screen makes Web sites hard to read and hinders the user interface in places
Occasionally slow to respond to taps
Verdict
The HTC Wildfire looks and feels like a cut-down HTC Desire, but that's no bad thing. Its low-resolution screen doesn't show the powerful Android operating system at its best, but we can forgive its blurriness when the phone offers so many software and hardware features at such a low price
Taken from here:
http://reviews.cnet.co.uk/mobile-phones/htc-wildfire-review-49305967/