Asus A8N eh? I
think that's a socket 939 with DDR RAM.
Do you know if the grpahics card is AGP or pci-e slot?
Chipset fans can be bought easily enough and Maplins do do them, I've seen them in there.
If not from Maplins, they're readily available on line and Zalman actually do a passive (fanless) chipset cooler, which is good.
Buy a new PSU, always a good investment.
The question then is whether to keep the existing motherboard/CPU/memory or whether to upgrade.
If your computing needs are modest I'd suggest just buying a new PSU (at least 500W and a quality make - about £60.00) and a new chipset cooler
btw, when you say chipset I'm assuming you mean the Northbridge on the motherboard and not the graphics card cooler.
You may also want to buy a new case to completely change the appearance of the thing and then hopefully you'll forget it was once a Mesh
The Antec Sonata case/500W PSU combined is a good buy at around £80.00 and imo is a good looking case, it's all shiny black.
If you want a complete upgrade then you're looking at new:
Power Supply
Motherboard
CPU
CPU Cooler (maybe)
Memory
Graphics card (maybe)
So yes, a Novatech base unit does seem like a good idea.