It most certainly would be better if you used a kernel more suited to your system.
However as I am not a Fedora user, I would suggest you wait for better assistance from another Fedora user. I would hate to ill advise you and render your system unstable. I'm sure there's a way to add your kernel source from the commandline.
Even though you no longer have the installation dvd, you can still use
Yum to add or remove packages. You may only need to update the
/etc/yum.conf file with the location of an online source for Fedora packages. This site may be of assistance in that respect:
http://www.tuxmagazine.com/node/1000038/print
It may be that it is no longer called the
kernel-source, it could now be called
kernel-devel in which case the one for your current kernel can be found here:
http://fancy.se/fc5updates-repoview/...t__.group.html
Here's the link to a very useful site:
http://rpm.pbone.net/index.php3/stat/2/simple/2