Not enough Available Memory

I have 2.31GHz with 2.00 Gigs of RAM with a Quad Core Phenom 9600 processor from AMD and now I am getting a message that I do not have enough available memory to run FS9.
What in the world is going on? I have run this program with lots more planes and helicopters available and now I am getting the message?
I cannot understand this happening, does anyone think that I should re-install the program altogether or should I do a fresh install of Windows?
I am very unhappy with the system as it now stands. HELP!

See if this helps.

http://www.w7forums.com/fix-your-system-low-virtual-memory-t6248.html

Radarman, I'm running Windows XP. This is the perplexing problem, I have run many many planes before this and just in the last few days did I get this obscene message.
The link that you gave me is more for Windows 7 and I don't know if that really applies to Windows XP. If it does please let me know and I will try it,
it seems logical but I really want to be sure if this is the case before I start messing around with the page size and then can't get back to the original.
Thanks so much for all the help!

XP.

http://support.microsoft.com/kb/826513

Thanks again RadarMan! You're the best!