When he says ideal resolution he means native resolution. Most (all worth considering purchasing) 24" monitors run 1920x1200. This is about a 40% increase in graphics load over a 1280x1024 resolution.
You may consider purchasing a monitor that supports 1:1 formatting (like widescreen TV sets, when receiving a non-digital signal). In other words, you'd be able to game in whatever resolution you like, with the picture surrounded by black bars, and still be able to have your windows desktop all big and stuff. However, there'd be a decrease in quality at any resolution other than its native resolution no matter what you do.