Windows/Microsoft Updates wont download & install...?

Hi all, obviously I really need your help and thats why my brother suggested I come here.

My problem is that Windows/Microsoft updates have stopped working completely even when I try to do it manually.

I am still using Windows XP, I also use Spyware Doctor with Anti Virus and Uniblue SpeedUpMyPC 3.

Up until about 2 months ago I have had no problems with everything working together in harmony and apart from the updates, everything seems to be still working great.

Then one day I notice that the yellow shied icon for Updates is in the bottom right corner of the screen (as usual) but is not downloading, its just sitting there saying "downloading 0% and will do that for hours, sometimes it will stay there until I restart my PC (which is every 3 to 4 days).

I have tried everything I can think of and nothing will work (but I am no expert).

Can someone please give me some advice on what to do because as of today I have 48 updates waiting to be installed.

I hope I have been clear enough, if not ask me anything you need to know.

Thanks x

P.S. I posted this in Windows General but havent had any replies so I thought I'd try this thread as well.