Literally last week my motherboard went phut, and I went round the corner to my friendly local computer company. After discussing it with them, I went for a new motherboard, an upgrade processor to the Athlon 1.6GHz and doubled the memory to 256 - just over £200 after discount for friends.
Existing hardware was ok, although I did have to re-load my HP scanner and Quicken software. Difference in speed is startling.
In a previous life I upgraded a 286 to 386, having been given a motherboard free from a relative. I followed an instruction book on how to do it and was largely successful. However, one or two minor glitches caused me a lot of time and grief to get sorted. Unless you are completely comfortable with the hardware and how it works (in depth), I would go with Evo7 and leave it to the professionals.