lots more then you can imagine, I'm running multiple browsers, and testing software all the time, I test lots of softwares and have a freeware site and I don't add apps inthere like othersites like fileforum or softpedia (more like soft copy ya) do
throw in the smp folding and you see I need more, half of the stuff I do now I would not be able to do with 2GB of ram. you probably would not recognize your pc with 4GB of ram, I would not recognize mine with 2GB
looked at 64 I think it was 2 years ago, and yup till this day still is not gonna help me at all due to compatibility.
I'm self employed so ya money is not that much of an issue, I throw over $200 a month into a dedicated server for the site and forum plus hosting others apps and our own, but its good since we are not money motivated you see no ads in our main site or our forum and we are clean as a whistle when it comes to our site and apps we have/host.
I have been thinking about a server setup for a while but waiting for Nehalem to decide if I go server:
Nehalem-family processors have eight cores. Coupled with 2-way threading, these processors appear as 16 logical CPUs. This threading is dynamic: Threads can be powered on and off depending on the application needs.
I can really use 16 logical CPUs, OK maybe not but it would be great