That's a double-edged sword. To answer your question truthfully:
Yes, Dual booting can be done without any problems
..and at the same, you may have problems.
This can depend on many factors (what OS's you are trying to dual boot, the order which you install the OS's, what hardware configuration you are using, and if Mr. Murphy is waiting around the corner to screw you over; LOL)
In my personal experience, the easiest dual-boot was with Windows XP and Linux (pretty much any distro). The rule of thumb is to install Windows first, then Linux. The reason is because Windows likes to pretend it's the only kid on the block and does not like to recognize other Operating Systems, whereas Linux will say, "Okay, Windows, you are sitting over there and that's fine, here let me give them an option to boot to you."
If you install Linux first, then Windows, it can be fixed but it is more of a hassle.
Also, I have seen some issues around dual-booting Vista and Linux, where Vista has become unbootable. Once again it can be done, and many have done it successfully, but there have also been problems.
Ideally, in my opinion, you want to have 2 HD's (one for each OS). Basically, you unplug 1, and install Windows on the other. Then you unplug the Windows drive, and plug in the other and install Linux. Then you plug them both in and during boot up you press whatever key accesses your boot menu and choose which drive (and thus, which OS) you want to boot. This installs the OS's in separate environments, less chance of things getting crossed.
When you have decided which OS's you want to attempt dual-booting with, hit the forums for those OS's and start searching for anecdotal evidence, tips, tricks, and mistakes.
I have had very successful dual-booting systems that in no way corrupted my PC, and I am currently dual-booting 2 Linux Distros (Fedora Core 7 and Ubuntu 7.04) with no problem at all.
The short if it is, if you want to try dual-booting, give it a shot. You won't know what it will be like until you do it. And if it doesn't work, do some more reading up and try again. Make sure you have all your data backed up! Then all that's at risk is the time it takes to format and reinstall.