Kannan, welcome to the forum! In addition to the tool that Veedaz suggested, which I'm positive is a good one, coming from him, there's another. One that you can use for daily cleaning. CCleaner has a "free space" cleaner, plus much, much more. You can clean as you delete your files, overwriting them up to 35 times, if you want to take it that far. But keep one thing in mind, with the "free space" overwriters, if you clean 100% of you free space, you may overwrite all of your restore points. You certainly don't want that to happen.
You have another option, which actually recovers your deleted files, so that you may choose to recover or delete the found files. A two in one deal. The program name is Recuva, written by the same group as CCleaner. What you do is a "deep scan", which may take a while. Afterwards, you have the option of recovery or deletion of the files. They also can be overwritten up to 35 times, but on a large drive, this will take some time. You can actually use your computer while the files are being overwritten.
So Kannan, with the three above choices, I'm positive that you'll find one or more that will work for you. If you use CCleaner to delete you files, rather than the built in disc cleaner, these files won't build up on you so bad. But your downloads, you can just dump them in the Recycle Bin, then empty it. Your temporary internet files, cookies, and so forth, CCleaner will handle the task just fine.
Best of Luck,
Cat