Although the same swap
file cannot be shared by linux and windows, I think it should be easy enough to have the linux swap file on the same partition as the windows one. However, follow these instructions at your own risk.
Make sure that your windows partition is set to auto-mount at start up (check the FC3 FAQ for details), and then create a swap file in the partition (I assume the partition is mounted at /mnt/win/c)
dd if=/dev/zero of=/mnt/win/c/swap_linux bs=1024 count=16000
This will create a file with null data of size about 16MB. Now use mkswap to make this a swap file -
mkswap /mnt/win/c/swap_linux
And now, add a line at the end of the file /etc/rc.d/rc.local
Code:
swapon /mnt/win/c/swap_linux
This automatically uses the file for swap space, every time the system starts. I added the line to rc.local to make sure that it is executed after the windows partitions are mounted.