Building a HTPC is not unlike building any other computer system, the only real difference is your choice in components. Against popular belief you don't always have to go with the smallest components you can find. In fact any old PC will work.
Business software left the office and moved into the home long ago. If you've ever lost the password to Word, ZIP or PDF file in misguided attempt to protect data from prying eyes, this guide to Decrypting Document and File Passwords is a life saver. PCSTATS Tips