Hi,

I'm interested in game performance mainly - and the processors mentioned are the Northwood 533MHZ FSB 512kb l2 series.

If it costs nothing go for it. If it costs anything i wouldn't bother, just save your money and get a new computer.

Not sure about games, but I got a decent performance improvement going from a 2.4GHz Northwood to 3.06; partly down to the hyperthreading, as the main performance-intensive apps I use are multithreaded and typically run around 30% faster than single-threaded.

As mentioned though, if it's going to cost much money then upgrading the whole PC may make more sense.

Well that's the thing, quite costly on ebay - I would get one if it was from a local dealer though for pretty much any low price... how about performance - how many percent increase (rough estimate?) 2gigs of ram and a good AGP card.

Honestly.. I would save the money on the RAM and AGP card and the Processor and get a new motherboard/processor/RAM/card.

Indeed. Save your money and buy a new rig. PCI-e cards are usually MUCH cheaper than their AGP cousins. You would be surprised what you can get for a small budget.

P4s are basically worse than the cheapest celeron today. Just get a new computer. It wont be worth it unless its free.

If all you needed was a cpu, maybe, but if you need all that, you will be wasting your money. Save and build a midrange rig.

If it costs you $30 or less to upgrade, I would. Anymore money and I wouldn't. Basically the HT will help a bit with multi-tasking and multi-threaded apps, but the difference in speed will not make a substantial difference in performance.