Any MS Project experts out there?

[Free Range Otter]

At work I am trying to set up a project plan using MS Project 2003. The problem is that the way resources are allocated at work, nobody is full time or can even dedicate the same number of hours to my project each week. For example, Bob can only work on my project 10 hours this week, 18 next week, 27 the week after, 6 the week after that, etc. All of the resources are like that.

Is there an easy way to define these hours per person (Mary has different hours than Bob) so that when I assign tasks they will fall into these defined hours?

Sorry, I know this isn't a computer forum but you are the smartest people I know and I'm hoping someone is good at Project...

[CookingWithGas]

This is the Help from Project 2007 that explains how to do this, but I don't know if this feature was available in 2003:

A new resource, Ashley, is starting work on this project about a month from now on June 1. Ashley will start the project working half-time, and then on September 1, Ashley will go to 75 percent. On January 1, Ashley will be 100 percent on the project. You use the General tab on the Resource Information dialog box to set the availability (javascript:AppendPopup(this,'pjdefAvailability_14')) dates and their corresponding units. You then add the Available From, Available To, and Max Units fields to the resource view so you can always see Ashley's availability for the current time period.