R G said:
...Would there be any complications accessing windows 2003 from a Windows 7 Home PC?...BTW the server literally has a SHARED folder with the program on in it.And the that folder then gets mapped on the PCs having to run it.
You may luck out and everything will run smoothly with a few simple mods on the clients ...but history tells us that is unlikely.
But, the short answer is yes, there will likely be complications. The degree to which that impacts the usability in a particular network topology can vary significantly. The impact can range from requiring low-level configuration manipulation (e.g. registry manual editing) to non-operability and dataset and program support elements (e.g. dll) compatibility issues.
For example, the Home versions of Windows generally cannot join a domain without using manual workarounds, and those still may be unable to provide full networking functionality in some situations.
Search the internet on something like
[ Windows 7 home clients and windows 2003 server ]
You may also find instructive information from more long-term historical experiences by searching on
[ Windows XP home clients and windows 2003 server ]
Whatever you decide to do, it would be a good idea to try all the program sharing, dataset sharing, dataset access control, emailing, printing, etc. that you plan to do with one licensed client before you pay for the additional licenses. This may uncover such things as the necessity of sharing (and providing lock control for) datasets with separate applications installed on the clients as opposed to a single application on the server...which can further complicate the compatibility issue.
Regardless of the OS installed on your clients, don't forget there is also the legal book-keeping issue of ensuring your licenses allow the clients you intend to use.
edit to add:
I also don't know to what degree, if any, applying mods to 'Home' clients (to fool them into networking as though they are 'Pro' or 'Enterprise' clients) will have on network and workstation security. I have personally never tried to gimmick-up a 'Home' OS installation to run in a business environment. I don't consider the minimal up-front license cost savings to be worth it...compared to increasing the complexity and therefore increased cost of maintenance, possible increased maintenance down-time, possible loss of functionality/compatibility (possibly at the most inconvenient times), and potential unquantified increased risk of compromising network security.