HP is the only competitor
... Dell and IBM's networking is either non-existant or woeful.
ProCurve, for switches at least is very, very good. They lacked a routing or security appliance when we moved from 3Com to ProCurve so we're using Juniper for our routers and firewalls, however the ProCurve's do a great job including Layer 3 routing between VLANs, superb management and very open when it comes to standards.
However the boss blagged a couple of the high-end switches from Dell. Awful management interface and not exactly reliable either.
Believe Dell just OEM some cheap chinese kit which is substandard, whereas HP own and develop their own networking stack.
Can't really comment on IBM but they aren't exactly the first company that spings to mind for enterprise network kit.
Our HP and Juniper estate works very well, and is a fraction of the cost of a Cisco setup. (Although we do use just Dell servers running ESX! :-))


ARM+GPU = dream super?
Nvidia's Maximus: Hard-core 3D graphics on speed