Registered RAM's have a ECC (small chip at one side) - error check control.
these are slowers as error checking slows down laetncy process as data has to pass through error check controller. these type of ram's are generally preferred in servers, not in work stations/desktops.
Unbuffered/Un-registered are faster, as they havent got anything like that.
you cannot say that system makes no errors, every system does, as if somehow u control the errors via RAM's what will you do to avoid errors in Processor pipe-lines? install another ECC there?. best is to go with Non-ECC/Unbuffered/Un-Registered RAM's
Intel Core2Quad 2.66Ghz 12MB L2-Cache
4096MB DDR Kingston Hyper-X
XFX 9600GT AlphaDog
Seagate 2 X 320GB SATA2
LG L246WH Flatron 24"