Removed boot flag and formatted partiotions in ubuntu...System wont boot!

Hi,

I had purchased dell vostro 3546 with ubuntu installed.After downloading gparted application i tried to partition as i wanted to install windows7 and I have by mistake deleted the boot flag.I might have mistakenly formatted the other partitons to ntfs.Now the system wont boot and ends up showing a blank screen.

Now can I just go ahead and freshly install windows7 or is my deleting the boot flag in gparted going to cause a problem?

P.S:I do not want ubuntu on my system anyway for any dual boot.I do not need any backup either as its a new system.So if it gets uninstalled its alright.Please help.