Not only that, but a G530 will offer nothing to near nothing over a E6550 or faster. I can't find a comparison of anything that slow, but the Pentium benches I can compare are not thrilling. If the price was high enough to include a near-3GHz SB Pentium, Core i3, or quad FX (for AMD IGP goodness), new would be substantially superior. A Core 2 or Athlon II X2 with 2+GB RAM will be good enough for quite some time (but if 2GB and used, going to 4GB now, before DDR2 gets too expensive, would be nice for the future).
I'd rather get a ATX over BTX, but that is one thing about used computers--beggers and choosers and all that.
IMO, if he doesn't want to touch it for many more years, a Core i3 with 8GB RAM (just because DDR3 1333+ is cheap) would offer much more value. That, of course, is part of why they can still get $100 for a Core i3. That extra $50 would help a little now, but do wonders in 3-5 years.