Windows XP SP3 Failed and stops other programs too!

I tried update from Microsoft, Started to install after download. Then just
sad Failed. No code! Rebooted Laptop, found that AVG, Acrobat Reader and
other programs no longer work.
Add to that that I have tried manual download, Go to install and informed it
is on laptop already.
Control panel opens, but, does not let me open Add or Remove Software.
Something else that no longer works.
So, no manual fix, no code, no readers and lost the use of programs, and no
internet security.
Any ideas would be fab as Microspft don't give a monkies unless I pay them
too.
Yours in-need, Paul from www.shoutdiscop.co.uk and www.shoutdiscoshop.co.uk