I recommend DriveCrypt, and especially DriveDrypt Plus Pack -wich means full disk encryption in realtime. That is fully invisible to user and does not affect performance. You must type your password before windows starts, and if you want, yo can create second password to bring up "clean" operation system (WinXP if you like) from encrypted partitions free space. When you start that special use OS it overwrites your original OS and sensitive data, so you can use this feature if you are pushed to open your files for investigation or in robber situation. Whole disk is allways crypted, so any data leaks are nearly impossible. Btw. encryption is over 1300bit (256bit AES and some else algorithm used same time). I must check TrueCrypt if it can handle enought powerfull algorithms to satisfy my needs of data security. Hope you got some help in this case.
