Have you got somewhere very secure to lock the bike up at work?
I would normally suggest that people buy the best bike they can afford, but since you will be mainly using yours for a short commute, I'd be tempted to save money and buy a cheapish but ok bike. If you really got into cycling you could keep that as your commuter bike and buy a more expensive bike later.
I just checked to see if the Sirrus Elite has fixtures for mudguards and a rack, which it does. I would definitely want those on a commuter bike.