Mac Os gone and only windows shows up, Help me.

I bought macbook pro 13 inch with OS X lion couple of days before. I triple partitioned it using rEFIt. I installed windows XP in one of them and it was working fine until I got to the point where I need to install drivers for XP (at that point, I didn't know that the drivers should be downloaded from server). From the boot camp assistant, I have downloaded the drivers not before formatting the windows XP. After downloading the drivers and burn into to the disc, I again triple partitioned the mac HD using rEFIt (windows xp -50 GB, Ubuntu - 40 GB and rest for Mac OS X Lion). No problem shows up during the partition. After installing the windows XP and restarted the macbook pro, to my surprise there is only one HD showed up and that is windows XP. I logged into the windows xp to check the drive capacity. The 'C' drive's size is around less than 50 GB and it s pretty clear that the windows XP is installed in the correct partition. But Where is the mac os partition ?. Its missing. I think, the mac os is not erased and it should be there. how to get that back?


Thanks,.

Thanks for your reply.

Command + R during the boot up is not initiating the recovery process of OS X Lion. It seems system is not recognizing the mac os.
I have installed Windows 7 by replacing the windows XP. Disk management shows the 50 GB NTFS partition, 250 Gb unallocated memory and 641 MB CDFS partition.

There are no sensitive data in the mac. All I need to do is reinstall OS X Lion as it was before. My Mac book pro shipped preloaded with Lion and no OS CD is in the box. How to fix this now?