Hey, leila:
I was having a terrible time with lagging computers when I first started, but it was completely a networking problem, and it was easily fixed once I knew what to look for.
Now, I have 7 PCs (wired), two tablet PCs (wireless), and one laptop (wireless) running without a server and it runs lickety-split.
If we had a few more details, we could give you better advice about whether a server would be helpful for you.
Here's for starters:
How many physicians? How many patients?
How many computers? How new or old are they? How are they connected to each other -- wired or wireless? What operating system are you using?
We can get into other details, but that would get us started.
