STYLETHREAD -- LET'S TALK SHOP!

okay, here's the deal.  i work in a small office as an administrative assistant.  two weeks ago, the only other admin assistant got a new job and left.  she took care of the majority of the accounting and all of the computer support for our office.  i run/organize the education and training programs and also do some accounting and general admin tasks.

before she left, my (former) coworker trained me so that i now know how to do a lot of her tasks (website administration/updates, etc.).  i feel pretty confident that i can do her job now, except for IT support stuff- like if somebody's computer crashes, i won't really know what to do.  but i can go to campus trainings and learn that stuff quickly.  anyway, now my boss (the "big boss"- he runs the whole place) is going around telling everyone that i'm the new "IT person."  and my other boss (my direct supervisor) told me to formally apply for the position. 

the problem is, for the past two weeks, i've essentially been doing two jobs for the price of one.  i've been so busy that i didn't even have time to officially apply for my coworker's old position until yesterday.  i'm already very underpaid and i've been here for a year and a half and have not received a raise.  (that's not entirely my boss's fault- i work for a large public university and due to budget cuts and union negotiations, nobody has received raises in a few years.  basically, the only way to get a raise is to be reclassified or get promoted to a new position.)

at one point, my supervisor asked me if i thought they should get a temp.  (i felt like saying, "ummm, why are you asking me?  you supposedly run this place/make the decisions.")  she also said that i was welcome to work overtime (uhhhh, no thanks!  how about a raise??).  i said that there is too much work for one person to handle, so it would be best if they figure out something soon.  and now two weeks have gone by and they're piling work on me and nobody has said anything about getting a temp to help out or officially promoting me.  they're totally taking advantage of me!

one more thing, i hate my current job.  i've been job searching off-and-on for the past few months and have gone on a few interviews.  so i'm not at all committed to this place.  but i'd be willing to take this promotion for now because a.) it's more money, b.) it would give me a lot of new skills (mostly computer) that could benefit me when looking for my next job, and c.) i'm ready for a new challenge.  i could do my current position in my sleep. 

i think i really need to say something to my bosses.  how should i approach this?  help!