I am a one-man IT department for a small company in Norwich.  Though my title is IT Director, I do it all.  I have a side project for one of our clients to do (a Flash feasibility study) an I was told that "all company work comes first."  However, taking this advice realistically means that I will never get to the client's project.  I recently made a list of my current projects (mostly database development and coding, debugging, etc for a web-based application we produced) and other ongoing IT duties (network maintenance, backups, etc).  We are also setting up an offsite disaster recovery location with full redundancy and failover for our web apps and database.  There is a lot to do.

In my attempt to get these projects organised, I input all of these projects into MS Project (its what I have).  I broke each project down in to sub-parts and linked them properly.  However, right now the projects are in MS Project as if they were all going to be done concurrently.  A few of them can wait until others are done but most of them need to be in work at the same time (e.g. one of our in-house programming projects AND the client's project AND the disaster recovery project).  However, since I am the only resource available to be added to any of these projects, I am torn (no pun intended) on how to make sure that the projects get worked on simultaneously.  Should I devote certain days of the week to certain projects?   I already write Mondays off because of meetings and organisation.  If I go this route I have no idea how to code this into MS Project so I can give management a realistic view of my schedule.  I would love to show them that there is too much work for me to do and give them a reason on paper to hire additional personnel.

Any advice is welcome.

There is only 1 right answer to this question... Prioritisation.  How you go about that is the tricky part.  In my experience, the best way to do this is to actually have your business partner prioritise, though for now that doesn't sound too possible.  I would suggest weighing what will deliver the most "value" (sometimes value is in perception, so you have to gauge this one carefully).
     Focus on the things that will enable making other things easier as well.  Not all tasks have the ability to be made easier by certain things, but some do, so look for those.  Don't let others put their monkey on your back either... this is how you really get bogged down, and lose valuable time during the day on the "Fire-fighting" instead of making real progress.  I know this sounds vague, but so is my knowledge of what you are trying to juggle.
     At the end of the day, don't be afraid to just say, "I'm going home" when you pass a "reasonable" hour.  Sometimes resting yourself is the best thing you can do for your future productivity.

Good luck.

Best Regards,
Reece

Technical question:  how to make MS Project show that Mondays are not available for project work.

Answer:
1.  Tools | Change working time
2.  Click on the "new" button
3.  In the popup change "Copy of Standard" to "XYZ Company", click the radio button next to "create a new base calendar", click on OK.  "Create a new base calendar" was chosen because someone may have played with the Standard calendar and this way you can be certain you get a clean calendar.
4.  In the pop up that shows the new calendar click on "M" (for Monday) to select all Mondays; click on the radio button "Non working time"; click OK
5.  Project | Project Information.... in the popup change the calendar field to "XYZ Company" (or whatever you entered in step 3), click on OK.
6.  View | Gantt
7.  Right Mouse Button on the Gantt chart and, in the popup, choose "Non-working time"
8.  In the popup click on the radio button "In front of task bars", click on "Calendar" and choose "XYZ Company" (or whatever you chose in step 3).

You're done.  Tasks will no longer be scheduled on Mondays.