On Windows XP, I'd start with a "chkdsk /R". (/R: "Locates bad sectors and recovers readable information"). Fire up a command prompt to run that command. Under Windows 9x, (95, 98 and Me) I believe scandisk has an option to do a surface scan and repair as well.

Within Windows, you'll want to open My Computer. Right click on your hard drive. Select Properties. Choose the Tools tab then use the Check Now button on the Error-Checking Section.

That should get you started. And don't be surprised if it takes rather a while to check through your disk properly: I've seen it take many hours to scan through a disk, especially if it's a large one (say, more than 20GB). Also remember, because the C drive is your primary partition you will most likely have to reboot to allow ScanDisk to run before Windows fully loads. If that's the case, Windows will prompt you and let you know what's going on, so you should be able to step through without any problem: if you do have a problem come back here and let me know about it and I'll help you figure out the solution.

Logical bad blocks are irregularities on the magnetic part of hdd, formed due to extensive read or write operations, caused by viruses, corruption's in the boot records, sudden voltage surges etc. The software for bad sectors remove logical bad sectors and repair your software.The Disk Repair software is a hard disk utility that can help you repair the logically formed bad sectors. Repair Disk Software realigns your hdd magnetic orientation so it can allow to read and write each byte. This way hard disk space recovery becomes very easy. At a high level formatting (through the Format command), the sectors contained in the bad sector table are skipped. Accordingly, there will not be any sector marked B ("Bad Block") in the FAT, although the defective sectors remain on the disk. Defective sectors are not removed, but merely noted in this table of bad sectors, resulting in the system ignoring them. We could say that the sectors are hidden. The best program to be applied in the procedure is the manufacturer's one, given on the respective utility page. If new bad sectors keep occurring after running this procedure, you should get rid of the disk, as its magnetic surface is deteriorating, for some reason.