Re: Thinking of upgrading my graphics card to an ATI 6850. Which should I get.
XFX, Gigabyte, Asus etc are basically re-branded versions of the same card, by ATI/AMD (Or Nvidia)
Some add better cooling, some overclock beyond the manufacturers spec.
When it comes to overclocking though, this can be done manually by yourself, so I generally wouldn't pay too much more for an overclocked card. Perhaps one with better cooling, i.e being quieter would win me over to parting with slightly more cash however.
They are essentially the same card though, so they should par with each other, performance wise.
You may also get the odd card that has slightly more memory (i.e 1.5GB as opposed to 1.0GB or even 2.0GB). The higher the memory on the card, the better the card will perform at higher resolutions with higher texture quality basically (Were talking over 1080P for more than 1.0GB in my opinion)
As for the PSU you have in your machine at the moment, I too have no idea from the specs you have listed. Generally if yours was a pre-built machine from the likes of Dell or similar, it won't have a very good PSU, and so yes, you should upgrade it.
The latest graphics cards need quite a bit of power, and a cheap power supply, i.e like ones built into cases will not supply what is needed safely for long periods of time.
You are best off getting say a 600-650 watt power supply, from again, a good manufacturer like Antec, or similar. Definitely don't go for the cheapest available in a range. Look at the typical wattages, and then check the price. You will find they will all run into the same sort of figure on the better manufacturers, and then you will get cheap £20 ones for example. Avoid them.
You'd probably be looking into the £40-£50-£60 range for a good PSU.
Any idea what motherboard you have? It should have the available slots needed, but its still worth checking. It will need a PCI Express 16x slot.
If you open up the case, the slots are usually labelled. The power supply also normally lists its wattage too.
A good website I've always used if in the UK as it seems like you are, is Micro Direct.co.uk.
A similar site, is Scan.co.uk.
I've always found Micro Direct to be slightly cheaper though, and the shop is closer by me if anything should go wrong after delivery.
Abit IP35 Pro / Q6600 G0 / Zalman 9700 / 8800GTS 640mb / 4x 2GB Corsair XMS / X-FI Xtreme M / 1x 1TB / Antec 900 / Logitech Z-5500 / Samsung 20inch