Thanks for the replies. I'm seriously considering rooting the phone so I can get all the apps currently on the phone onto the SD card. The lack of memory is driving me crazy. However it seems very daunting to root the phone and it's not helped by the myriad of ways to do this with no-one able to explain the safest and easiest method. I am hoping that a colleague of mine may volunteer to do it for me as he's rooted a few HTC's in the past.
Have a look at the rooting FAQ, which you can find by following the red link in my sig (takes you to the root forum sticky thread "all about rooting").
There are actually only 2 sensible ways of rooting a Desire:
unrevoked or
revolutionary (for people who've applied the official Gingerbread update only revolutionary works). If you want to keep the current ROM but remove system apps then you may as well use revolutionary, which fully unlocks your system storage and allows you to just delete things. It can be done without, but this makes it much simpler. If you just intend to load a custom ROM then either will do.
Both are rather simple to use. If you use Windows there's some faffing with drivers before you can run it. But once that's done, it's a case of plug the phone in, run the tool, one click to confirm you want to procede, and that's it.
It would probably be more appropriate to move a longer discussion to the root subforum. The key thing is to read the rooting FAQ first, and to take note in particular of the stuff about "erase sizes" to ensure you install the correct custom recovery for your handset. It's straightforward enough, but it's best to understand it first, in order to avoid problems that might arise through overlooking some important detail (like the one above).
It's also good to know why you want to root - rooting in itself doesn't change very much, just gives you the options to do other things.