Mountain Biking - To Upgrade or Not? & What Parts Does this Chick Need?

I currently own a 2005 Marin Hawk Hill. With Fall approaching down here, I really plan on doing on a lot more riding when the weather gets nice(or make that bearable lol). I've been looking at some parts online and would like to upgrade the bike a bit....hopefully by myself. Luckily, one of my roommates seems to know about bikes and has offered to help with the upgrades. I'd like to upgrade the front and rear der. to either Shimano or SRAM higher end stuff(LX or X7 stuff). How do I know what size to get...some of the specs are confusing to me). Also want to upgrade to disc brakes. Can I do this with the 05 Hawk Hill? Was also considering SRAM twist shifters instead of the trigger shifters I currently have(I just prefer them). What do I need to get that will work on my bike? Anyone know of anything specifically? I need specific parts and models cause that is what I will order online. I'm new to this stuff and a girl, but I'm really interested in biking and I'd like to know more about the mechanics of it all.

This is a link to my bike with specs:

http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=2005&Brand=Marin&Model=Hawk%20Hill&Type=bike

My bike does NOT currently have disc brakes however like these specs state. I have the basic Hawk Hill model and I think it has V-Brakes. I'm assuming that since this frame does have disc brakes, that mine should be able to be upgraded? Am I wasting my time upgrading this frame? I thought that Marin made a decent frame and this would be more economical than buying a brand new bike. Any thoughts?

Last night I finally attempted to swap out my tires with some new ones I got a few months ago. Not quite as easy as I thought it would be. Took about 20 minutes just to get the old tire off the front rim. It was a pain in the *****. I didn't have a tire lever or anything, just did it by hand. The new tire went on much more easily. Still have to do the back tire...but I had to get to bed last night and didn't expect the front tire to take so long and be so hard to get off.

Thanks for any and all responses. I could really use ya'll's advice, suggestions, and help.

Checked the Marin Archive and according to this:

http://www.marinbikes.com/bicycles_2005/html/bikes/bike_specs/specs_hawk_hill.html

My frame does have disc mounts...will this make a disc brake upgrade easier? Will I still need tabs, brake parts etc.?

The frame and fork are disc compatable, but your hubs are not. You can get your LBS to lace on some disc hubs fairly cheap. ( Avid bb5's or 7 brakes FTW )
The fork is the area I would concetrate on if I were going to keep the bike. I'm sure a lot of people will recommend a whole new bike.
I probably would too. But..........
I have been known to throw a A good chunk of money into a frame that I really liked.

...it doesn't really look like it's worth upgrading it until something breaks. I'd wear it out like it is, and save up for something better.

The bike you have is not a bad bike at all. It doesn't have pro components, but they are decent, and will take a good beating. A while back when i got back into MTB riding. I bought a 07 Gary Fisher Wahoo "no disc" and Alivio components. I must say the bike rocked, and I beat the hell out of it. I also weigh 240, if that tells you anything about how well it held up. Anyways i was in the same boat as you, I wanted to upgrade and make it nicer, after pricing what it would cost to get a new fork, disc hubs, disc brakes, and new derailer's. It was just a little less to buy a nicer bike, and thus I did. Allthough, I will admit before doing so, I did upgrade my front and rear derailer's to Deore, but I found them used on craigs list cheap. So if you can find used parts cheap, go for it,if not,buy a new bike.