You have an open malware topic at http://www.bleepingcomputer.com/forums/topic425622.html
and it appears to me that you have received a fair amount of help thus far...so i have to wonder about your comment re "xtill waiting for the result".
As for reformatting vs reinstalling...reformatting is part of reinstalling. It's necessary to format in order to install any version of Windows. Formatting is part of the Windows install process.
If you don't intend to reinstall Windows, then formatting the hard drive/partition is a necessary step in preparing the drive to be used for storage of data files.
There is plenty of documentation available on the Web...if you have any questions about installing Windows, reformatting a drive/partition, and such.
If you have an OEM syxtem (any laptop is an OEM system), then the procedures for installing Windows are governed by the manufacturer of the system. Such procedures should be detailed in the user/owner manual and/or at the respective website of the system manufacturer.