In their further efforts to make exchange 2007 completely unusable, Microsoft has also screwed up their send/receive limits management.
please see this link for a clear guide:
limits must be set in multiple places...
organizational configuration: hub transport, global settings tab, transport settings properties
Server configuration, hub transport, select your recieve connectors, and select properties, and modify the Max message size field.
organizational configuration: hub transport, send connectors tab, select your connectors, properties, modify the Max message size field.
Lastly for individual mailboxes:
Recipient Configuration, select your mailbox, properties, mail flow settings tab, message size restrictions, properties, and set them as you like.
Here is the thing, an individual user's limits can exceed the global limits, but ONLY FOR INTERNAL MESSAGES. For external use, you can not.