I've been using LogMeIn to access my office computer while I'm traveling (to get access to things that are internal to the office). So far it's worked well, even accessing a Windows machine from my MacBook.
The only problem I've run into is that the Java file transfer doesn't work under Firefox - it locks up so you have to kill Firefox. This is mentioned on their support forum, but so far no solution. It works from Safari though, so it's not a big deal.
The basic version is free. I decided to pay for the Pro version since it was relatively cheap and I could use some of the Pro features.
There's a bit of a lag in typing, but that's not surprising considering I'm using wireless to dsl from Mexico to Canada. Occasionally it trips me up, but for my usage it's fine.