Got an assortment here. Usually I fluther on a linux box built about three years ago with goals of low-power and big capacity (photos!). It has 4TB of drives that lower their speed then turn off when idling, and the processor is relatively low-power dual-core AMD brisbane.
Sometimes I use a Shuttle that I recently rebuilt with a new SolidStateDrive (fast!) and Windows 7.
We have a few Macs around, some old some new’ish.
Occasionally I’ll be online on an ASUS transformer tablet, very portable!