Protecting mah program

- I have written a program, I want people to pay for it
- It is a type of program I don't expect hackers to have motivation to hack (it's a recipe program)
- If the program doesn't receive a valid activation key, it goes into limited trial mode
- The activation key is the SHA1 hash of the installation key + a guid I picked.  They must enter this key to get out of trial mode.
- The installation key is the SHA1 hash of the hard drive model + serial number.  They get this and must email it to me with money.
- I don't expect typical users of this program to know how to spoof the HD serial number (lol females).
- Did I do this right?  Suggestions?

>>1
You will piss users off when they get a new PC / HD or when they reformat (if you use the file system serial number (most likely)).
Are you really scared that some housewife shares the key with her friends? If a key gets on warez websites somehow (how many housewifes use warez websites?), you can always blacklist it in later versions. You should at least give users virtually unlimited new keys.

Also, crackers are likely to crack any crapware that they come across (usually on sites like download.com), especially if it's really easy like your program. It's not really worth fighting though.