So I decided that I'd up the amount to 8GB, which would be 4 sticks of 2GB each. I then went off to look for suitable memory, and settled on a pair of Crucial Ballistix Tracer 4GB kits (matched pairs of 2GB sticks, DDR2 800MHz). Why that particular memory? Well, a good brand, 4-4-4-12 timing rather than 5-5-5-15, and heat spreaders to help keep it a bit cooler.
Note to mention the price: £50 + VAT per kit from Novatech. (No, don't look, it's now £75 + VAT per kit). They didn't have it in stock, but never mind, I wasn't in a hurry, this was a luxury upgrade, not a required one.
It finally arrived yesterday, and I installed it. It's nice RAM, if a little underutilised, but it was going to be future proofing. There's just one feature ...
That 'Tracer' in the title?
It means that there are LEDs on the RAM packages. There are blue LEDs along the pin edges, nicely lighting up the circuit board, and red/green LEDs along the opposite edge, merrily chasing themselves in random patterns.
It's a shame my case cover is opaque and that whole effect is totally wasted.