The color balance in general should not be altered due to the place the file resides - if you are looking at the same file on the same monitor, it shouldn't matter if the file is on your local PC or on the penturners.org server. There aren't any web servers that modify colors (at least not that I know of, and I've been in computing far longer than I like to admit, and have done quite a bit of tech support for graphic artists, and some of the color concepts have "rubbed off" on me.)
That said, different monitors have different color balances, and even on the same monitor one picture can appear dramatically different at different times of day, with different numbers of lamps on in the room, etc. You've probably been in Best Buy or some other superstore looking at TVs with the same picture on a whole wall of tubes, and it's startling how different they all look. Same thing applies to computer screens.
There's a whole science (or art) of making colors accurate, and a few years ago Apple came up with the ColorSync standard; Microsoft has created its own system called Image Color Management (ICM). Add in the fact the printing industry has the Pantone (R)Matching System (PMS) for hardcopy color calibration, and the whole thing becomes very complex. What it boils down to is that if one is intent on getting exact color matches, one needs to calibrate the monitor on one's computer to display colors properly. And if you want to print them, then you gotta do the same thing for the printer...
It winds up being more work than most people want to do. Myself, I don't worry about it on my home PC (just like I don't spend days getting the stereo balance and frequency response perfect on my home stereo, while when I'm in the recording studio, I am fanatical about it.)