Android phones, apps and tablets

So my Desire got an upgrade to 2.29.405.2 last night, but I had to remove quite a few apps to make space for the upgrade. What doesn't really make sense is once it was installed I can install all those apps and more again, so presumably it needs temporary space?

Is there any way round this? And are there any other files I should be trying to keep down/delete like temporary files?

I wish more apps supported move to SD.

You should've tried a reboot before removing stuff. It clears cache data and frees up space.