My personal experiance I reformat and reinstall at least once if not twice a year. the more you use the internet and visit site the filled with crap your system gets. especially when you install all the free stuff. I use windows virtual PC to try out new software its awsome. run wndows in windows and if it trashes the virtual PC who cares it was just a copy and just like doritos Ill make More. IRQ less than errors are genreally device driver errors from a drivers that have been damaged somehow. Maybe the machine got the plug pulled or got turned off with actually shuttung down. you could try doing a disk error check (open my computer then right click on properties then click on the tools tab then choose check for errors and do the cheack on startup and see if thats part of the problem. Maybe the new nvidia drivers have it all fixed? havent seen a post today. as far as credentials I have been working on PCs in one way or another since 1990. I am currently employed in a validation lab testing new motherboard designs.
edit ( in looking again the BIOS on the system is around 4 years old you may want to look into updateing the bios.)