Motherboards aren't terribly difficult. Of course, this is assuming you read the directions. These days most things are auto-detected, and if you have to set any jumpers, there's usually just a few. Just make sure to power the motherboard on outside of the case first.
Things you may want to factor in on the upgrade;
-Power supply. What you have in your current machine is probably not going to be enough to run an A64 setup.
-RAM: you need to have PC3200 DDR for the A64 route. If you go to Intel you'll need at least PC3200 DDR2, possibly faster.