What makes you think that a kernel upgrade will increase speed? Kernel upgrades generally don't have a performance improving aspect. Upgrading to a more recent version of a distro usually doesn't improve performance, either. Unless there are fixes for bugs that degraded performance, or there is a new algorithm used to improve performance, you will probably see no change. To improve performance of something that existed when Fedora Core 2 was current would probably mean a simple hardware upgrade: more RAM, faster CPU, faster disk(s), faster network perhaps, faster GPU (which might require a new driver).