Socket A was great, cpus and motherboards were so cheap my system was in a constant state of flux. Cheap barton mobiles were great too, great overclocker for less than what a desktop barton cost, with lower power usage to boot, and this was before nvidia started to segregate their motherboard offerings quite as much, so a $50 nforce2 mobo was as good as a $150 one (if such a thing even existed back then).
The platform really only came out on its own with an nforce2 chipset though. Big performance boost, and much more stable than the VIA stuff. Heck, stable, better featured, faster, and easy overclocking.
Just recently though, my dad still had a tigerdirect pc he put together a while back using some crap soyo motherboard, very insufficient cpu cooler, and an athlon XP. After messing around with it for a bit, I ended up just taking the harddrive, memory, and video card and buying a refurbished 2.8GHz p4 system off tigerdirect (athlon 64 systems were slightly more) for under $100 and slapping that together. Shame to discard a good platform like that, but it wasn't worth the hassle.
Also recently killed a laptop that used a mobile duron. Duron was great back in the day, but the small L2 cache kills it on XP or newer, tried to upgrade its harddrive with an ssd, stupid sony proprietary adapter must have broken.