We received a VERY extensive and useful consultant report from 'International Technology Group' which proofs that IBM System x, BladeCenter and System Storage have the
best TCO (Total Cost of Ownership) compared to HP and Dell. We urge everyone to read this.

Some of the results for these comparisons may be summarized as follows:
Server costs. Overall three-year costs, including hardware, maintenance, software, personnel and facilities for use of IBM System x and BladeCenter platforms averaged 12.2 and 8.9 percent less than for use of Dell PowerEdge and HP ProLiant and BladeSystem equivalents respectively.
Disk system costs. Overall three-year costs, including the same components as for servers, averaged 21.6 percent less for IBM DS3000 and DS4000 systems than for Dell/EMC AX4 and CX3 systems, and 22.9 percent less than for HP Modular Storage Array (MSA) and Enterprise Virtual Array (EVA) systems.
Combined server and disk system costs. Reflecting the differences described above, combined three-year costs for IBM server and disk system platforms averaged 16.4 and 15.3 percent less than for Dell and HP equivalents respectively.

Source:  Business Case for IBM System x, BladeCenter and System Storage (XSW03022USEN.PDF)