Want to Revert Back to SL or Lion From ML, on MBP w/o Losing Anything from My HDD?

Okay so I have ML on my MBP here at University. I have ML but it's way too buggy and many applications dont work, including my scanner.

I want to go back to SL or Lion. I have the original disc of SL and obviously purchased Lion from the Mac app store. Here's the situation though, that I dont want to lose anything on my 500GB internal HD. I'm utilizing 300GB's and can't lose anything considering my backup external HD is at home back with the folks; with no way of me being able to retrieve it till July.

Wondering whats the best solution for this.

Furthermore, I would hope I have the option of choosing either SL or Lion and not lose any of my data; hoping the decision is a matter of what I like; such as Spaces & Expose from SL, or iCloud and Photo Stream from Lion.

Any help is appreciated.

GibMcFragger said:

I am not going to tell you that you shouldn't be running a beta OS on a machine you need to rely on. Ok, I just did...

That said, unfortunately there is no way to downgrade without formatting your hard drive. I hope you have all your files backed up..

Click to expand...

I do have it backed up. Just do not have the external HD on me here.