OK I got two spare machine home now.
1) Proliant 40L microserver with a 1tb and 250gb HDD. 8gig ram.
Turion II Dual core (1.5ghz)
2) Emachines EL1850-UR12P, Pentium Dualcore 5800 3.2ghz, 8gb ram. 120gb SSD.
I'm thinking of seeting up ESXi just to play around and learn other besides windows 7. (windows server, MAC OS, Linux distros.. etc..)
which machine do you guys recommend for the task?