VLDBs on 6.5 and DBCC

Hi,

has anyone some basic information, expericence and numbers on how much a DBCC (chechdb+newalloc with index, singl-user mode) will take for three DBs all in all about 40-50GB Data(20/15/15), concering CPUs, Memory, IO-Subsystem?

Which one is most important? IO-Subsystem, CPU, Memory ?

Is running parallel DBCC on each DB an alternative or is step by step better?

Target is: Reduce the time DBCC takes by any measure...

I need some real life, no theory!

thx in advance
Thomas Wolloner