completely erasing a drive help!!

So here's the deal. A while back I installed bootcamp + ubuntu 10.10 on my MBP 2010 15", resulting in a triple boot.

I now want to delete ubuntu and bootcamp along with it. However, here is the situation I am facing.

In the partition tab of my HD I got 4 partitions (dunno what happened there).

1. disk0s1
2. Machintosh HD
3. BOOTCAMP
4. disk0s4

disk0s1 takes up only 200mb and for some reason it is showing disk0s4 as taking up some 440GB. My HD is only 500gb and more than 300GB is allocated to Macintosh HD.

disk0s1 and disk0s4 are grayed out and I cannot do anything to it.

Is there a way where I can delete everything, make the HD one partition and restore with time machine?

thanks!

 

after I reformat the drive do I have to install the OSX first or do I restore from the installation menu?

 

thanks for your reply!

One more question. If I install a whole new OSX instead of restoring the whole system from the start, can I then choose specific files that I want to restore through the time machine?

Also if I do a fresh install instead of a system restore, how can I keep my Mac App Store apps?