This is more than you need for just the monitor... but at this price why not be safe? (you could even bump up to the gaming-ready 4670 for $60)
A larger monitor will run better with 1 gb of ram on the card. 512mb is good for must of us at 1440x900 and below, but you probably want to spring a little extra for the memory to get the best performance on a large monitor.
*I dont know if your computer is a slimline or full tower--but if its smaller keep that in mind when purchasing.
** At this low-level card you shouldnt have to worry about your power supply.