Hi uchkur,
Sorry to hear about the hard drive issues you may be experiencing.
Conventional wisdom would be to replace the hard drive, but despite being very inexpensive these days, if you have no money that is not a suggestion that you can implement. 
Current prices in the Uk for a 500Gb SATA drive are around GBP £30 and about GBP £20 for slightly smaller capacity drives ( that would equate to around USD $40 and USD $27 at current GBP/USD exchange rates (however when I have purchased computer equipment and spares from the USA I have found them substantially cheaper than those available in the UK…and of course there are also well known Internet Auction sites!
I would advise you to think most carefully before embarking on a fresh installation of Windows and there is no guarantee that partitioning in the way you suggest would achieve the result you desire.
All may not be lost with your existing set up…the fact that hd tune found a few unstable sectors need not mean that your drive is going to fail immediately….although a fair few technicians would regard it as possibly indicative of a precursor to future trouble.
Usually the unstable sectors have not yet been re-mapped to exclude them from writing/read duties, but if read write issues crop up in the future may well do so.
I would be inclined to follow the following steps:
1 Check your back ups and system images, for reproduction ( verify if possible) make sure they include everything that's important to you. including a full Registry back up) and any stuff you don't want to lose. Make sure that you have at least 3 copies of everthing with one kept safely offsite on removable media. Don't forget to look out your installations discs ( executables), product serial keys, including those for Windows itself, and that your ethernet and wifi drivers are all safely to hand on removable media.
2 Try to repair your operating system, start with running a disc check with something like Seatools and download your hard drive manufacturers disc repair utility and run both the short and long tests. If those tools can repair the issues then all well and good but often hard drive issues start small and do tend to escalate over time… so start saving for a new drive.
3 It's worth while running sfc /scannow ( from an elevated command prompt) to have Windows check for damaged or missing protected system files
4 It's also worthwhile considering running your on board anti virus product and a good on demand scanner especially if you have been using risky procedures (torrents for example)
Don't try anything before you check your back ups…. disc repair utilities can stress a hard drive and you don't want to "push it over the edge" before you are 100% happy with your back ups.
Good luck
Regards
paws
