google bought servers from dell, and from rackspace or some other vendor. I helped run a fleet of dells with 15K SCSI drives for google (mysql workload) that was absolutely critical and it took the company a decade to replace the dell machines with "white box" (really, self-designed and externally manufactured) servers.
What Google did different than the rest back in the days was mostly relying on x86-32 with Linux and not so much RISC (SPARC) with Solaris. Sun's market share was huge back in those days.
