iSeries TCO v NT server farm

I thought it would be easy to find a TCO that someone has done comparing
an iSeries to an intel based server farm, but I haven't found anything
of note.

I've got a project that I'm pitching that works via thin client.  That
means we can pretty much use anything to pump out the html.  

I'd like to use iSeries because of it's great uptime and phenomenally
stable database.  There is a suggestion to use clustered NT servers on
the table as well. The reasoning of management is that it will be
cheaper to go NT, and that customers will more easily understand an NT
server based solution.

The project is mostly CRUD (Create/Retrieve/Update/Delete) via a web
browser.  Probably 200,000 transactions per month, and an audit log of
every phase of the transaction, perhaps 5-10 audit records per
transaction.  There will be an interface between two other systems, as
well as general reporting and file maintenance activities.

Most importantly, business is 24x7.  This application, once live, can
probably withstand short downtimes in the wee hours each day, but not
much more.

Anyone have any good TCO links?

Thanks.

Regards,
Rich