As obsidian86 already pointed out, Raidmax is not known for quality power supplies. Luckily, your current pc configuration does not require a lot of power, just don't push it to the limit.
For the future, the general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the 12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 4770, 5850, and 5870 cards which use a little less power due to their energy efficiency.
Corsair, PC Power & Cooling, and Seasonsic are some of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Lately we've been seeing a few other brands offering some high quality units.