Personally, refurbished systems are not worth the money. These systems by their design crap out after use. So you are buying someone elses headache. IF it was an N64 with no moving parts.. MORE POWER TO YOU.. but an Xbox with DRE and PS2's I say the 10$ savings is fools gold.
While I'm not too sure about the Xbox's 'quality', never, never, NEVER buy a refurbed PS2. As Ron can tell you (and I can confirm, as we both worked at EB at one time), the original PS2 design was simply designed to fail and were built by morons. We'd get shipments of consoles all the time that were defective.
The GBA and Gamecube are great refurbed machines - never heard of a system going bad on them. The Xbox had the occasional issue with bad/old DVD drives, but beyond that, it's a pretty solid system.
The old PS2 design was crap.