eMac issuses and Leopoard install question

i just booted up my eMac for the 1st time in atleast 3 months and come to find out its not running as smooth as it did 3 months ago. i use Trillian and when i learned there was a update i got it just to find out the latest Trillian does not work on PPC so heres my problem i sign onto Trillian on my eMac and it work but it will not connect to MSN or the Trillian Astra network (all other messengers work fine) MSN works fine on my Windows machine as well as the Astra network i tried uninstalling and re installing i have deleted the Trillian folder in the Library still no success Trillian was workin fine 3 months ago.

Second i listen to Last.fm on a semi-regular basis this loads on my eMac and it does work however after i play 1 song thats it it will not play anymore only way to get it to play is if the last.fm window is visable and not minimized to the dock. This was also a problem that didnt exist 3 months ago.

This video shows that its possible to run Leopard on a G3 by installing it (leopard) on a g4 then putting the HDD into a g3. is this even possible?

http://www.youtube.com/watch?v=20_p6FTF0nA&feature=related

 

i had 1.5GB RAM in the thing but the 1GB stick died when it was sitting (all it did was beep) i pulled one stick at a time and found out its only running with the 512MB