Last post was right, you provided too little information about your "stuff"
I run WindowsXP Media Edition and Solaris 10 11/06 on the same box, and thats what I can say for sure:
There is no problem to run both of them (it's always good to combine both powers in one), If you meant that you worry about loosing your data, then just back it up somewhere, Solaris installation is the same as any other OS. So make a partition and install as usual.
Solaris 10 is not for gaming :( but it does include video and audio player, plus most of the popular ones have versions for Solaris OS, so there should be no problem with it. Also Solaris support viewing pictures, if you dont like pre installed ones, then search for other software. It also has StarOffice which works as Microsoft Office, but just better I think. It more powerful and brings you better way of doing what ever you planed to do.
I think I dont need to tell you that solaris just makes programming very easy (supports everything with easy way to set up, not writing code for you...well actualy it does if you use studios).
So s a conclusion:
Solaris same as Windows, Linux and Mac. It does everything what a person needs to do. But if a software is made for one OS there is no way to run it on the other...unless you use simulation of some sort.
Although be warned that Solaris 10 have problems with drivers for PC boxes, so before you swich make sure that everything will work or you can set it up yourself.
Here is a program to check if your hardware is supported or if there are unofficial drivers for it:
otherwise here is a link to the HCL (hardware compobility list):