I'll assume your old dell board is bad; if not, I wouldn't change it for 100 pounds. The only upgrade option with ddr and agp for 100 pounds would be a used socket 939 board with dual core cpu, which goes for a premium, since they are getting scarce. And most 939 boards have pci-e slots, except for a few off brands and the nforce3 chipset. You may end up ditching your agp card anyway. Check ebay uk, then look up the board specs under "archives" on the manufacturer's website before ordering. If your dell board is good, consider selling your old system intact before it fails and starting over.