Thanks for your input.
Just to clarify: My current Antec PSU is still working, although SpeedFan* reports my 12V voltage at only 9.86V, so I'm thinking the SmartPower may need to go. So, with my current specs (i5-750, 1 HDD, 1 DVD-RW, 1 ATI HD4850), do you think I need a bigger PSU? If so...