plugins gone

ok, I just installed two plugins. A demo of drumagog and amplitube version 2. I a using sonar 6 on windows xp. I hit scan for plugins and it found both of them but It deleted my other vst plugins so I no longer have vintage channel and ......I can't remember the other one but anyway they are gone. When I open a project that uses them it gives me a warning that the plugins are no longer available and if i save the song they will be permanently deleted. Which I think they already are. I can go into the computers seach for files and find vintage channel stuff but it asks me to select the program or use the internet to find the appropriate program to open it with. anyway. What the heck? under the help it says to reinstall the plugins. If I just reinstall sonar will that work? Will I loose any of my projects? Any other advice? Also If I were to upgrade to sonar 7 (which I am thinking of doing) how easy is it to transfer projects over. Do you have to save everything and import or will it automatically recognise previous projects? Sorry for all the questions. Any help would be great. P.S. Amplitube is pretty cool!