There are some differences that you should be aware of between using FMP as a client and using IWP. I would suggest you take some time reading up on IWP to save you a lot of time while designing your system. This was you will not have to re-create your system when you find out things do not work the same way with IWP as with Pro.
I will have a read....
Also check out the differences in global field behavior between networked and single user files. On the whole, the differnce makes global fields extremely useful in network versions, but the change does catch people by suprise the first time around.
See this knowledge base article: http://filemaker.custhelp.com/cgi-bin/filemaker.cfg/php/enduser/std_adp.php?p_faqid=2984&p_created=1115172664&p_sid=AIeD31Bj&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MjYzLDI2MyZwX3Byb2RzPSZwX2NhdHM9JnBfcHY9JnBfY3Y9JnBfcHNfYW5zX3VwZGF0ZWQ9JnBfcGFnZT0xJnBfc2VhcmNoX3RleHQ9Z2xvYmFsIGZpZWxkcyBuZXR3b3Jr&p_li=&p_topview=1