Yeah, we just got one recently and have a similar setup to you...
2xHP switches in the blade chassis, connected to a single (for now) Cisco 6513 using trunks/etherchannel.
I have 2 links from each HP etherchannelled to 2Gb each to seperate blades on the 6513 until we implement a second (this one's only for livetest/dev stuff). These are trunked so that the blade servers themselves can be on different VLAN's to fit in with our Livetest architecture (which is what we're gonna use it for).
The hard part is getting used to the different syntax i.e. a trunk in HP isn't what I'm used to as a trunk in Cisco etc.
If you need any help give me a shout and I'll do my best!
Anthony.