I never tried to install Mac Os into a Intel based PC, not even in my wildest dream. So I have no experience how far the installation process has damaged your file system, boot record etc. The symptom that you are experiencing means two things:-
1. Only the master boot record is damaged. If that is the case , good news - your files will be back.
or
2. Needs fresh installation.
Is there any system restor CD associated ?(came with your laptop at the time of purchase). In that case place that CD into the drive and reboot. Follow the instructions and you will get your old OS back.
Things will be different if there is no system recovery CD. With a windows installation CD try to recover your OS. If you need a fresh installation - apart from windows installation CD you will need lots of drivers (for Display, bluetooth,wireless network, sound card etc) and letest patches for H/Ws. Download all the drivers you may need from Lenevo site.