Getting $250 back was an awesome deal.
And I hate to rain on your parade, but I'm really amused how you keep talking about how you want a high quality viewsonic LCD panel, when the one you got apparently didn't last 2 years.
Take the $250, and add whatever $ you need to get some other brand of LCD. I'm not sure what would make you want to stay with viewsonic given the performance of your current monitor.
And if they would have given you CASH, that's an even better deal, you don't have to get screwed by compusa again.
You should go back, apologize sincerely to the manager, and tell him you'll accept his offer of returning your $250 cash and that you had time to think about it and realize it was a very fair thing for him to suggest.