Sure, just add them to your Favorites first. Then open favorites, right click it and copy. Now right click on your Start button, choose Open. Now click on Programs, then click on Startup folder. Right click and paste the file there (something.url will be the filename). Do the same for the other two websites. You're all set now. But this only works when the computer first starts.
Want to be able to make those 3 launch at anytime by clicking one thing? Just copy and paste all 3 favorite files (something.url) in a folder (maybe create c:\temp and put it there).
The something.url might be very long named, so rename it to something easy like 1.url, 2.url and 3.url
Now open up notepad and type this: Yes, each one goes on a new line (note the first line, just change to the folder you saved the .url files to):
cd \temp
1.url
2.url
3.url
Now click File, Save As, and save it as: choose any filename and end it with .bat (ie launch.bat).
Make sure you type "launch.bat" when saving (yes do add the quotation marks too). This means save it literally as what it sees in the quotation marks. If you dont' use quotations, then your file might look like launch.bat.txt (but even if that happens, just rename it to launch.bat
Now create a shortcut on desktop (right click desktop, create New Shortcut). Point it to the .bat file. Now whenever you double click the .bat file, it will execute each line in it, line one would be change directory to the folder where the .url files are located. Line 2 says launch 1.url (which would be your first favorites location, etc.