Graphics Card Advice

Hello, I was wondering which graphics card would be ideal for the ECS P4M800-M7 motherboard.

I currently have the nVIDIA GeForce FX 5500 (NV34) graphics card, but know this particular one is not very good at all. Time for an upgrade! I'm not that computer savvy when it comes to hardware, so any help would be very much appreciated.

I'm willing to spend atleast £150 ($244).

Thank you in advance.

Information:
Processor Name: Intel Pentium 4 630
Original Processor Freqency: 3000.0 MHz
CPU Code Name: Prescott 2M

Video Chipset: nVIDIA GeForce FX 5500 (NV34)
Video Memory: 256 MBytes of DDR SDRAM

Memory Type: 2 x 1G DDR-SDRAM
Memory Speed: 200.0 MHz (PC3200)

Motherboard: ECS P4M800-M7
Motherboard Chipset: VIA P4M800 Pro/CE/CN700 + VT8237(R)

If any other information is needed before I make a decision, just ask.

Edit: I use this computer to play video games, such as World of Warcraft. I'd like a graphics card that can give 40+ FPS, and not the constant 12-20 the FX 5500 pitifully throws out lol

Thank you for your reply! I appreciate it.

Unfortunately, NewEgg don't ship to the UK. I think I'm going to go with the more expensive option. Can anyone suggest an alternative to NewEgg.com? So far, I can only find the Sapphire version, and not the HiS version in the UK.