Easier ? first - YES, disablign remote assistance protects Your system. It means that Your system won;t allow someone else to connect to Your system and run it like they're sitting in fron tof it (Thus - "remote desktop").
Now, as far as Linux being used to replace Windows, yes it can. it can also be used alongside it if you use either a multi-boot system or a "Virtual Machine" program like MS Virtual PC2007. These programs allow Your system to dedicate some power to pretending to become a different type f computer for some purpose, in this case - running Linux.
Now, as far as being used to replace Windows again - You need to be aware of a cpl facts first. Windows runs on an underlying computer language called DOS. no matter which Windows You use, there is a version of DOS that's letting it run on the computer's hardware. When Windows is installed it is simply a collection of programs that is created to show You certain things and pass certain functions through the underlying DOS and hardware drivers, which creates results that are then shown to You.
The place Linux fits into this scheme is that it's basically a replacement (alternative actually) DOS and hardware drivers set that is used for programmers to create the software that runs it.
This means that - if You look hard enough, and someone who actually programs for Linux decided to get along with it for a little while instead of despising it, You can basically run a completely copied version of all the Windows programs under a Linux DOS and hardware drivers set.
So, f You're thinking of just using it like Windows, You'll have to find a combination of the DOS (in Linux it's called a "kernel") and hardware drivers and the programs that run on it to get as close as possible to "the Windows Experience".
If You want to test out a copy of it and see just how hard this will be - some people have over 20 yrs experience and still haven't mastered it, just install MS Virtual PC2007, and create a virtuial machine for the Linux installation, then start the research on versions, requirements, and available programs for web browsing, emails, Powerpoint and databases, etc ....
You could also just buy a used hard drive about 40 to 60 Gbs, and switch it into Your system whenever You want to screw around with Linux, Freespire, Linspire, GNome, Red Hat, Linus, or whatever.
Good Luck!.