Please help

[beaner]

Hi there told to come to this site by a guy who was doing some plumbing for me (that sounds weired) any way i need some help with a graphics card.
I have a dell 5150 pc pentium4 3.0ghz processor,512 ram,70gb hard drive. The graphics card that came with it is a Radeon x300 se 128 mb. I would like to upgrade as my kids have brought me Unreal Tournament for xmas and this wont run very well. I am not that clued up on computers so that the reason i am here. Was told to get a 8800 gt from this site. Would this fit straight in to my pc as i see there is something about PCI express (not sure what this is)
Any info would be great (after you all stopping laughing at this question).
Many thanks
Beaner

 

[beaner]

Another ? what does PCI express mean, i take it the graphics card is the one which the monitor plugs in, it has a video out if that is the card. I took the side of and it fits in a slot like the memory does. Is that what it is. I really am thick.Sorry

 

[beaner]

OK guys think i getting there now so how about this (money is an issue kids and xmas),
Radeon x1950Pro and do i need to upgrade memory as that dont look to expensive.
Found the x1950 on here good price it looks, but there are a few different types would any of these do http://www.overclockers.co.uk/productlist.php?groupid=701&catid=56&subid=404
Once again thank you very much for your help peeps.

 

[beaner]

well guys i think you have made my mind up for me(you must be realated to my wife) this is what i gonna go with as it is in stock and just within my budget.
Memory
GeIL 2GB (2x1GB) PC2-6400C4 800MHz Ultra Low Latency DDR2 Dual Channel Kit (GX22GB6400UDC)
Graphics card
Sapphire ATI Radeon HD 3850 Pro 256MB GDDR3 TV-Out/Dual DVI/HDMI (PCI-Express) - Retail
Last couple of things if any problems do you know if i can send back to overclockers and get refund and was looking else where on reviews for this card and someone said there is a cable or adaptor needed from the psu to card, do i need to order this as well.
Thanks for everything.