You may want to search SSC for a solution. I know for a fact that this is not the first time your question has been asked in these forums.

You may want to consider a more formal auditing technique if it is feasable. An auditing procedure like what you've suggested will be a very poor performer on large tables as it will have to do a column by column comparison. At the very least, you may want to look at using a timestamp or datetime column to narrow the search down to only those rows where you know for sure changes have been made.