I have a PC900 ASUS with 4gig C: drive and 16 gig

Stop running so many applications.
You have less hard drive space on C: than I have memory on my computer. I am currently running 2.85G memory utilisation - if that was your laptp, that means nearly all of your disk is used up by virtual memory.
You can change your swap space to your 16G drive - go to desktop. right mouse on My computer> Properties > Advanced > Performance > Advanced > Virtual Memory
Change the location and size of your swap file.
You can also add more real memory - that is the most efficient and effective way to increase your performance as well.