Not using Truecrypt (free) but using Folder Lock (paid) instead. Check it out - I've found the user interface to be really very user-friendly and it's been worth the money (about $30, after discount). I don't use it on my NB505 but on another laptop where I have some serious data to protect. It also gives you an Online backup (for additional subscription fee), but I don't use that. Should work on your NB305 just fine.
Cheers!