of machines to your Mac - but just because you *can* does not mean you *should*. You didn't tell us what kind of Mac you use, what type of files the other users need to be accessing and saving, how large those files are, what type of network you have in the office, what computers the others are using... lots more questions.
If you have that many "people who need to be constantly connected to it accessing and saving files", then the performance of your computer - while YOU are on it - will degrade. This is not a Mac vs Windows item... this is a basic networking item. Lots of network IO means lots of work on the drive and on the CPU. Plus, the OS is not optimized to be a file server... XServe is...
http://store.apple.com/AppleStore/WebObjects/BizCustom.woa/6624009/wa/PSLID?mco=15D9D272&nclm=Xserve&wosid=3Q4NeSIzqOsd2afVtL8wnmK35OT
Rather than "using [your] Mac as a kind of file server", may I suggest that you either, (1) get a work group file server or (2) investigate the use of Network Attached Storage (NAS).
http://shop1.outpost.com/product/4913861;jsessionid=lPEwnsbyXkipWr+ZLFlRQw**.node1?site=sr:SEARCH:MAIN_RSLT_PG
In either case, I would strongly suggest implementing a strategy of doing proper daily back-ups (incremental and full - preferably to tape) and rotate the back-up media and all the other things that go with running a work-group server... Because if that 'puter falls over or the hard drive fails, the whole office is dead.
"Using [your] Mac as a kind of file server" may seem like an affordable way to what you want to do, but it isn't. I would not recommend it - especially in your stated "constantly connected to it accessing and saving files".
I know Windows XP Home and Pro limits the connections to 5 and 10 connections respectively.
We are thinking of using my Mac as a kind of file server for our small business, but we have about 7 people who need to be constantly connected to it accessing and saving files. Is there a limit to how many people can be connected at one time?

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