Database Size and user limitations on Navision

Anyone running a Navision Database greater than 30GB with 240 concurrent users out there. Can the system handle this number of users / transactions or is it pushing the boundaries for the technology.

Current system runs on a Citrix farm, using SQL 2005 and is expected to grow to 240 users.

Does anyone have any real life examples of  this size of database. What is the performance / transaction times like?

What is the optimum configuration in terms of hardware / Memory?