Need to render an fcp 7 project

Hello all, I was working on a desktop that crashed right before I could render a very important project. I bought an OSX 10.8.3, 3.1 GHz Intel Core i7. The version of fcp I was working on w/ the crashed computer is unknown, but I guessed my best bet was to buy tcp 7.0.3 (since fcp 10 is a completely different software & the higher I go in the older suites, the least chance I have of the fcp version being too old for the project) & install that onto my new desktop, hoping it will enable me to render my project. Anyone know if there are any issues I should be aware of? Or any resources where I can first check if I'd be wasting my time buying fcp for this desktop to save my old project? And has this ever happened to anyone else? (BTW the reason I have to repurchase fcp is because I hadn't bought it before- it was already installed onto the old desktop that crashed when I bought it. )

Am sorry but I do not quite get your question!

a) You had FCP 7 (probably) installed on a computer.

b) You crashed and did a clean install of every thing / lost FCP 7 in the process?

c) You are now thinking about buying FCP 7 to rescue the project?

Correct?

How complex is the project?

Do you have FCP X?

Have you heard of this here?

7toX for Final Cut Pro

nofilmschool.com/2012/02/7tox-final-cut-pro-work/