Big problem with Windows, my OS is gone.

[J o e l]

Alright I have a biggggg problem with my mac, and would appreciate any advice.
Firstly, the facts about my issue:
I do not have an OS lion installation disc
I do not have a backup (if need be I can backup my mums Macbook pro and use that if that is possible?)
I have a Macbook Pro.
I downloaded Windows by using the disc, not through bootcamp as it would only allow me to use a Windows 7 disc.
Alright, heres the problem:
Earlier today I installed Windows XP 2002 onto my Macbook Pro, I believe I must of downloaded it over the OS partition, a I can now only use Windows and that automatically boots up when I restart my computer. Holding down Option doesnt work, as the only one there is Windows. I also tried to do Command+R and re-install Lion, however on the last page it says something about my startup disc, it says:
Select the disk where you want to install Mac OS X
The only option is called untitled however this says: "This disk doesnt use the GUID Partition Table Scheme. and basically says I can't do it. I also do not have a disc as I bought it off someone and it came without it.
It does have the option to back-up my mac.
What can I do to resolve this?

Thanks for your help

Also would using my mothers backup work?

 

[\-V-/]

Lion doesn't have an install disc... it never did. It is downloaded from the Mac App Store. Lion has a recovery partition it creates during its first installation/upgrade.

Boot Camp doesn't download Windows so you didn't install Windows unless you used a Windows disc but I'm not sure what you're saying.

Lion doesn't ask about an install disc, it wants you to use your Apple ID to verify that you purchased Lion, which you didn't if you got the computer or OS from a friend. You can purchase Lion on the other computer then use the Apple ID you used to purchase Lion when it asks for that information and that will allow you to install Lion.

 

[J o e l]

Right, I used a windows disc and installed it manually, not through bootcamp, sorry for the confusion. Will I have to re-purchase OS lion?

 

[yashii]

hey i installed window vista on my Mac book pro via bootcamp,,, i knew it only give Window7 option but installed Window Vista on it and after every time i started my computer it bootup with Window Vista,,, doesnt give any option to pick OSX Lion or Window Vista,,, dont know what wrong i did but appreciate if anyone can guide me to recover lion back