Upgrading PC need advice

  peeps this is my first post and i am going to get straight to the point.

I'm a laptop user and i was given a pc that has been sitting in my cupboard for a while and when i opened it up with a friend to check out what was inside it.

as you can probably tell with it being a free hand me down PC that the components of it were very basic (as my friend told me) but this has been the first desktop pc i have ever had.

He said it can be upgraded.

So i play Team fortress 2 on my laptop and i have to have all settings down to low and while using fraps at most i get 20 FPS and most of the time get an average of 15FPS
so it plays really slow on my laptop.

anyway...

The pc has an

ASUS A7A266 motherboard

A crappy graphics card

512MB Ram

40GB HDD

so...

I was wondering as i only really want to play Team Fortress 2 and maybe COD4

i know i will need to upgrade my memory so i have already decided to put in 2GB SDRAM

i will also be buying an Athlon xp 2600+ cpu

but what would be the best graphics card i can put in this as it will have to be AGP

i'm looking to spend about £50 on just the graphics card.

Is there a better CPU tht the board can take?

and also whats the best card at tht price or even just what is the best card that this motherboard can take?


All advice would be greatly appreciated

Thanks
MADsMoKe