novice question–are todays computers really faster than 6 yrs ago

I basically just burn cd’s, surf the web, watch videos, and do minor desk top stuff on my computer (which is a dell dimension 4600 with a pentium 4, 2.66ghz). Would I see a big benefit by going to a new mid level, or even entry level? I know this probably a silly question to some, but I have very nominal computer knowledge. Thank you