Re: best budget pc upgrade.
Recently bought an e2140 (38 pounds), gigabyte p31 ds3l (47 pounds) and 2gb ddr 667 (28 pounds) A motherboard can be purchased for a lot cheaper but i choose that one because it should offer a fair amount of upgrade ability in the future (motherboard and cpu from scan, memory from here Patriot 2GB PC2-5300 Signature (2x1GB) - Aria Technology)
Re: best budget pc upgrade.
good suggestions above, you will do good to go with them.
Re: best budget pc upgrade.
I'll second the e2140 - my first ever attempt at overclocking got it to 2.66ghz with the stock cooler, no problems so far and Orthos etc.. seems stable.
Re: best budget pc upgrade.
if you're not overclocking, a 4200+ can be had for around the same £40 mark on ebay, the GA-MA69G-S3H for about £46 on scan, and 1GB corsair xms2 pc5400 from scan is cheap (getting two sticks of 1GB is cheaper than a 2GB pack i think).
Re: best budget pc upgrade.
That graphics card sounds like it might be AGP, so make sure you get a board with an AGP8x slot (which should be cheaper than newer boards anyway)
If you are not overclocking - look at getting an AMD - Socket AM2 and something like the 4200+ X2.
If you want to dabble in overclocking Intel is a much better bet, and the E2140 is a great place to start.
Best price/performance ratio for RAM is probably going to be a 2GB kit (2 sticks) of 667MHz stuff :) - 800MHz better but a little more expensive and you wouldn't really notice the difference.