The simplest and safest, and perhaps quickest) step is just to do the step from Intrepid to Jaunty. No reinstall, just click a button and wait an hour. At this point there is very little to go wrong with this unless you've recompiled half your drivers or installed lots of weird stuff manually. Then you can go again if you're feeling confident.

If you don't have much in the way of non-repository applications and your own data is safely tucked away on a separate partition or backup up, then you can just install 10.04 or 10.10 and wipe out what is already there. Or if you have the space for a separate partition, install a new version next to the old one and get your data straightened out before you wipe Intrepid.