My company is trying to decide if we should upgarde to FM7. Right now we have FM5.5. Is it worth it to upgrade? What are the big difference between the two?

The answer to the first question is probably "yes". The answer to the second question is very long, cause it depends.

There isn't THAT much from an end users perspective that you can do in 7 that you couldn't do before, but from a developers standpoint, there are MUCH EASIER ways to do things that used to be very complex and/or time consuming.

Some features that really make a big difference to the end user are:

Better network performance, so you should be able to use the database remotely more reliably than before.

Better security (many improvements here)

As far as converting, my recommendation is a complete rewrite from scratch.

It might also be worth while to note that FileMaker says they will not honour upgrades from pre version 6 starting in September (I think). Frankly, I think this is really dumb, but I have a funny fealing that when the next major release of 7 comes out, they will "temporarily" offer it for older versions as well.

I would recommend starting right away and spending some time working with 7 on simple "prototype" files. 7 is in many ways the same, but in some ways so different as to be mind-boggling (in a good way, but it can be confusing).

One ability which users will certainly notice is the ability to open more than 1 window of the same table (and you can have multiple tables per file). Each window has an independent state, found set, etc.. Very useful sometimes. Several script steps to control windows, incl. size and placement.

Operations on related data are much faster. Finds on related data are quite tolerable.

As Jason says, many of the new abilities will be most appreciated by the developer.

The relationship graph must be seen and used to be believed. You can now access any data along a path (but no data not along the current relational path; though globals are available from anywhere).

Many script steps are slightly different, several are added. Almost all steps can now specify their parameters directly (Import, Print, Sort, Find, etc.); multiples of these steps can be in the same script. Buttons can access many more script steps directly; they can also include a parameter, which the script can access.

Security (Accounts and Privileges) is somewhat the same, but so enhanced as to be a different animal, with script steps also.

Many new Functions. A section on Text Formatting. Text formatting is now preserved by the calculation engine; great for custom form letters. Values functions (to work with lists). Let function (just like the big boys :-/

You should get Developer, because Custom Functions can be built and included for use in any FileMaker files (many are available for download). File Maintenance can be done; the equivalent of saving a clone and importing all the data, ie., an optimized file, all in one step. Trim MB's of excess fat :-)

Unfortunately, there's also the odd "insect," like with importing, which I imagine/hope will be squashed with the next upgrade. They'll be fixed by the time you're ready to get serious.

Read these (especially the "foundations" one):

http://www.filemaker.com/upgrade/techbriefs.html