£50 = $102.48 USD
Assuming you have a PCI Express X16 slot.
From fastest to slowest.
ATI Radeon HD 2600 XT ($100 USD)
ATI Radeon HD 2600 Pro ($85 USD)
ATI Radeon X1650PRO ($39.99 USD)
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My opinion for a new video card:
For playing the latest games at full settings, a FRAPS (frames per second) of 50 or higher (80 or more optimum)
For moderate games a FRAPS of 30 or more.
For simple games or no games a FRAPS of 18 or more
Refer to:
http://www23.tomshardware.com/graphics.html
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FRAPS (frames per second); higher is better per
http://www23.tomshardware.com/graphics.html
NVIDIA 8500GT ($59) FRAPS=17.5
ATI Radeon X1550 ($30) FRAPS=22.5 est
ATI Radeon X1650PRO ($39.99) FRAPS = 30.8
ATI Radeon HD 2600 Pro ($85) FRAPS = 33.6 est.
ATI Radeon HD 2600 XT ($100) FRAPS = 47.7
NVIDIA 8600GTS ($133) FRAPS= 53.6
ATI Radeon X1950PRO ($130) FRAPS= 53.8
ATI Radeon HD 2900 PRO($280) FRAPS= 88.1 est.
NVIDIA 8800GTS ($269) FRAPS=102.2
ATI Radeon HD 2900 XT ($375) FRAPS = 108.6
NVIDIA 8800Ultra ($549) FRAPS=116.9
Prices in USD per newegg.com
X1550, X1650, X1950 Support DirectX 9
All others support DirectX 10
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Power requirements
ATI Radeon X1650PRO
http://download.hightech.com.hk/manual/X1650PCIe/mk0703004_X1650_PCIe_manualV2.pdf
450-Watt power supply or greater recommended
ATI Radeon HD 2600 series
http://download.hightech.com.hk/manual/HD2600/radeon_hd2600_users_guide_137-41353-10.pdf
A 550 Watt or better power supply.
NVIDIA All
http://www.evga.com/products/moreinfo.asp?pn=256-P2-N624-AR&family=18
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Higher performance video cards require more current from the 12 volt leg of the power supply that supplies the video card. This may require changing to a more powerful power supply. Determine the amps at 12 Volts the video card recommends and compare it to your existing power supply.
How to Buy a Power Supply
http://www.wikihow.com/Buy-a-Power-Supply
Nvidia SLI Certified Power Supplies
http://www.slizone.com/object/slizone_build_psu.html
EVGA Approved Power Supplies
http://www.evga.com/articles/286.asp
ATI Radeon Crossfire Certified Power Supplies
http://ati.amd.com/technology/crossfire/buildyourown2.html
Diamond Video Cards Certified Power Supplies
http://www.diamondmm.com/certified.php