I will check regarding the hardware sizing requirements, we had a beta version of that, but I don't know whether it was published - I will be back.
since service tier is 32 bit. would it run faster on 32 bit os or 64 bit?
What was the decision to keep it at 32 bit?
The decision was timing - there is a small piece of the old unmanaged code that hasn't been moved to managed code, and we cannot compile that to 64bit. Without promising anything, I would say that I would be surprised if the next major version comes out 32bit only
I don't know yet whether the servicetier would be faster on 64bit or 32bit - I don't think the difference is huge, since the entire app is 32bit - I think the difference would be higher if the same application where to marshal back and forth between 64 and 32bit with state and all.
So why didn't we hold the release?
On that one I think that we needed to show the market (both Customers and Partners) that Microsoft is betting on NAV. NAV is a strategic product and we have invested a lot in getting as far with the platform replacement as we have done - and we will continue down that path. NAV 2009 is already later than we would have liked to - and the 32/64 bit doesn't really change anything for the migration of applications and stuff - but it does hurt our scalability.
Also what is memory requirement for service tier. How much memory can it handle?
We can use up to the 3GB which is possible for a 32bit app, which allows you to run approx. 40-50 users on one Service Tier.
On my blog I have posted a couple of threads regarding how to setup multiple service tiers.
One of the things I will do is to setup a beefy ServiceTier computer (just recieved the box yesterday) running Windows Server 2008 64bit with HyperV and see how service tiers performs on hardware like that.
Hope that answered your questions.