this is first time i installed fedora core on workstation.
Now its takes hell lot of time to open excel or word (openoffice.org)
I ahve RAM 256 MB but it shows 128 MB however on other windows PC its shows 256 MB.
Even if I leave PC idel for somtime then also it responce little late.
So user in my company thinks window's excel or word is faster then Linux.

What to do ?

What kind of machine is it and how are you finding out the amount of available RAM? If Linux is seeing the wrong available RAM, it could be a buggy BIOS or something.

machine is celeron with 633 Mhz processor
and IM CHECKING RAM with 'free' command

I do I knw that BIOS is buggy.
if it is, wht should I do to make BIOS alright??????

Well, the reason I mentioned the BIOS is that that's the only reason I can think of for the amount of RAM detected to be different in Windows and Linux. How do you tell if your BIOS is buggy? Well, when the system boots, one of the very first things you see should be the BIOS version. It should says something like "PhoenixBIOS", "AmiBIOS" or something like that and then a version number. Once you've got that, do some searches and see if you can find any examples of others having this problem. Or just find the website of the company that makes your motherboard (you'll probably have to open the machine and look at the actual board if you don't know who this is) and download the latest firmware update, which will come with instructions for installation.

But remember, the BIOS thing is just a guess. Needless to say the problem you describe is very unusual. I remember a similar problem with Compaq machines due to a buggy BIOS, but that was about 6 years ago.

Apparently no one here is very sure. Here are some other resources you might ask your question to before messing with the BIOS:

The fedoranews.org fora: http://fedoraforum.org/forum/
The fedora mailing list: http://www.redhat.com/mailman/listinfo/fedora-list

Try those and see if anyone can help.

Good luck!