list *all* available package updates using XMLRPC API

Hello folks!

I'm trying to query the RHN XMLRPC API in order to generate a list of 
all the available updated packages for our various RHN-subscribed hosts; 
unfortunately, what I get from the API and what I get from `yum 
check-update` differ dramatically.

For example, running `yum check-update` on a host that's currently 
running RHEL5.3, I see 176 updated packages available (that's the 
RHEL5.4 update).  However, when I issue the 
'system.listLatestUpgradablePackages' API call, I only see updates 
available for packages associated with specific errata in RHN, which is 
a much smaller subset.

Is there a different API call that I should be using that will give me 
an equivalent list?

thanks,
-Steve

-- 
Steve Huff - Systems Administrator, HMDC - [email protected]