For what is is worth, you will most likely get the best service with your Mint 5 install if you stick to the default kernel that came with it. Everything has been set up to focus on that kernel. When you change a kernel, it can have unforeseen consequences. You can update to a newer kernel in Synaptic if you acknowledge there may be breakage. If you go with a whole new kernel not officially supported in Mint or Ubuntu yet, all bets are off as to what the result might be. Though, if you are the adventurous type, you may find success. Just be aware there can always be a downside. Experimentation is always the fun part of the learning process.
In my openSUSE 11 install, the kernel is 22.214.171.124-1.1-pae i686 running KDE 4.04 "Release 15.1." I have been tweaking and adjusting all weekend. It has plenty of bells and whistles, to be sure. I previously used the 64-bit install with version 10.3, but only saw minor improvements in performance. If you have 4 GB of RAM, then you should go with the 64-bit install. However, be aware that there are still some Java issues with 64-bit, so I am running the 32-bit version right now. There are a couple of openSUSE guys in here, so you can get their opinions.
Also, if you plan on testing out openSUSE, do not be tempted to get the Live CD of GNOME or KDE. You actually need the full DVD version. The extra time you spend downloading the 4.3 GB DVD will more than pay for itself in the long run. The torrent took me 23 hours to download, but I knew what I needed, so I suffered through it. I figured I was not in a hurry since I do everything I need in Mint 5 anyway. All that being said, I am sitting here drinking coffee and keying this in with Mint 5. Good luck, and please post back to let us know of your progress.