Buying advice - PDA for warehouse staff / goods-in

Hi all,
I'm new around here, so please take it easy!
Basically I'm looking for a bit of buying advice. I work for a small cheese packer and distributer and I am looking to issue our warehouse staff with PDAs. The purpose initially is to replace the current paper-based systems for goods in procedures.
I am imagining an access-style form on the screen, so ms access compatibility is important. So is robustness (they have to warehouse-proof!). I'd like the data to update with the main server either live or periodically. Other than this I really don't know what I need to look for. There's such a massive range out there.
So, I hope somebody here can help, and I thank you in advance for your advice.
Stephen