alsealey

I personally feel the Desire was released with a major flaw - the lack of internal memory for apps. This has now been solved by developers, each taking a slightly different approach. the great thing is this opens up a lot of options for you, but you have to do a bit of work for yourself.

The people on here will help, but can be a bit "have you read the guide first." They help so many people I guess it can be a bit annoying when the info is there.

Firstly I'd suggest you download gparted - it's free. Burn it to a CD (bootable.) You then restart your PC, selecting boot from CD in the menu - it will then load gparted (linux) from the CD. from here you can partition your SD card into 2 7/1 or 6/2. Do this with a USB micro sd card reader and put your memory card from your phone into that.

Have a look at the roms and see which one/kind you like the look of. From personal experience I would recommend either Cyanogen, or if you fancy a bit more work, SUroot's rom.

Dave

I am currently running is Cyanogen 7.1
CyanogenMod-7.1 for Desire GSM :: (V7.1.0) - xda-developers. It allows you to force apps that don't support apps2sd to the sd card as well. I have tons of stuff on my phone and still got 80mb free.

For Sense roms look at Leedroid ones.
LeeDrOiD HD V3.3.3-Port-R5 |11th August| Ginger Sense 2.1 | FAST | STABLE | WWE - xda-developers

Non HTC sense roms, look at
dGB v01_28_2012| 2.3.5| 375MB /data| 60MB /system |Mult-lang - xda-developers
Cyanogen or Oxygen roms.

There is also a kind of iphone ish rom called Miui.
Feb 10 - 2.2.10 GB 2.3.7 EN-MULT+OTA+CM+Updater|D2EXT X-PART|A2SD+|D2W - xda-developers

With regards to your phone - there are people on this forum, such as SURoot, Hadron that will help you. And it is a common problem, and one that can be sorted out. Do you like HTC sense or are you open to getting rid of it?

Rooting your phone will allow you to install a customised rom. Partitioning your SD card - what this does is basically divide it into 2. You usually assign (on your 8gb card) 6 or 7GB as FAT32, then following this a 1 or 2 GB (remaining space) as an ext3 or ext4 partition. An ext 3 or 4 partition is a linux file system that the phone will then see as internal memory when you use a customised rom. They use a script called apps to sd that basically allows you to move the apps to the SD card, which overcomes your problem.
Have a look here to see if there is a ROM you like. Stay clear of the newer Ice Cream Sandwich (ICS) roms - a lot are in development.
Desire Android Development - xda-developers