Once you're sure the PC is free of malware, create standard user accounts for each user and install an arsenal of free security programs and activity monitors to enhance the machine's virus resistance.
If Windows 7 takes more than a minute to start, it may have too many programs that open automatically with the operating system. Longer delays are an indication of a more serious conflict with a piece of hardware, a network, or other software.
A little change to your computer's interface can make it seem like a completely different machine. If you're getting tired of the standard Windows experience, why not try installing an application launcher?
Whether you prefer details, lists, thumbnails, or icons, making sure Windows Explorer always displays your files and folders in the view of your choice is more difficult than it should be. Freeware alternatives to Explorer may be just the ticket.