Well, I wasn't planning to do them all at once - in fact all I have done is remove Avira.
Got another BSOD last night, so obviously Avira wasn't the only problem.

WhoCrashed says this:

On Sat 30/05/2009 11:52:59 your computer crashed
This was likely caused by the following module: win32k.sys
Bugcheck code: 0x1000008E (0xC000001D, 0xBF809D10, 0xAEDE1884, 0x0)
Error: KERNEL_MODE_EXCEPTION_NOT_HANDLED_M
file path: C:\WINDOWS\system32\win32k.sys
product: Microsoft® Windows® Operating System
company: Microsoft Corporation
description: Multi-User Win32 Driver
The crash took place in a standard Microsoft module. Likely the culprit is another driver on your system which cannot be identified.

... Not very helpful.
Any ideas?

@townsbg: sorry, what? What emails?

Sorry I was getting 2 threads combined. I have removed that.

By googleing this error, the win32k.sys file in particular, I'm reading 3 possibilites.
1. driver conflict. To test for this I would uninstall and reinstall each driver one at a time (rebooting after and in between) if you can boot into your computer. If you can't normally try safe mode.
2. the problem is with windows being corrupted. The best way (and sometimes the only way) is to reinstall windows. Either way be it 1 or 2 if you can boot into your computer I would make backing up your data the first priority.
3. faulty RAM.
Help thread (post)

do a repair install of windows xp http://www.windowsreinstall.com/winx...allxpcdrepair/ if that those not fix your problem test your Ram with this Microsoft Online Crash Analysis

A repair option is usually built into a retail copy of XP although I have found it hard to use. However a repair option isn't an option in some manufacturer's restore disks. If it isn't you will have to get a retail disk somehow or just reinstall. But I would back up files and try the drivers first if you can boot up your pc. If you can't then run a memory test. If that fails you will more than likely have to buy new ram. If it passes you will probably have to reinstall windows.

I shall re-install the other drivers one at a time, with a week in between each, then if I still get BSODs after that I'll re-install windows.
I don't have faulty RAM - I've tested it with MemTest86, and besides I paid the extra charge and maxed out the system with Crucial memory - guaranteed for five years.

Re-installing windows is a bit of a pain (mainly because of the time it takes to re-install all the applications I have set up), but I'm not too bothered if I must. I do it every few months anyway, just to clear up and speed up.

Thanks for the help.
I'll post here if I learn anything else.