The usual problem with a slow boot, (aside from malware, but you don't seem to be asking about that), is too many applications loading at startup.
Whether you have sufficient RAM or quad-core or whatever, if you have too many apps loading at startup the system is going to bog down. Everything is trying to load into RAM at once, besides the normal OS files, services and processes that are essential at startup, and the cpu is swapping in and out of too many things.
I would ask myself the question. Do I really need all these apps loaded immediately I start the computer? eg, I can start my browser myself. I can start any IM when I want. I don't need any Real Player software started, nor any other media players. They will start automatically whenever I want to play some file or other.
Keep the Startup file list to a minimum, ie, any Microsoft files, the firewall, the anti-virus and anti-spyware background scanners.
i have a mean machine already - 3GB of ram and a quad core running @ 2.6.
why does my program load so slow? For instance, it takes forever for my yahoo messenger to load up. My computer boot is so slow too.
Though not all apps are slow - for instance, google chrome is fast.
Though once my app are all already loaded, then things are picking up. I can have more than 15 applications running on my task bar and my machine would still be in very good performance.
But what's with the slow startup when 99% of my cpu time is idle?