High Availability is not very hard, but as many things there are some learning curves.
For us the 2 main parts are DRBD and Heartbeat. It is best to completely understand both before setting up 2 servers in high availability mode.
As you have KVM, set up 2 containers to run heartbeat. Have it set so that between the 2 kvm's one i/p address is available at all times. then you can add other services .
Use Debian Lenny or Squeeze on both , install heartbeat and read /usr/share/doc/heartbeat/GettingStarted.html
There is a lot of help avail at linux-ha.org/ . for each part of heartbeat you are trying to learn check that site.
then ask questions and I'll try to help.