Yup the iPhone 2G and 3G has the exact same hardware (so slow). I tolerated the iPhone 2G for a long time since I was on T-mobile's network (unlocked) and edge was slow anyways. But I played around with my friends iPhone 3G and it felt the same as the 2G iPhone (hardware wise) and it was so slow! Only difference was that it had 3G enabled. Anyway I bought an iPhone 3GS sometime last year (moved over to ATT for 3G) and it was miles faster than the iPhone 2G/3G.
I remember while we were on a road trip and needed directions, I used the iPhone 3GS (pressed the home screen button from safari to get to the google maps) to do a quick search and gave the directions to the driver) while my friends iPhone 3G was still "loading" google maps.
And since we didnt need the directions anymore, my friend tried to exit google maps by pressing the home screen to get to Safari (so that he can resume surfing the web) and while he was still stuck on google maps to exit back to the home screen, I was already back on safari loading up my 2nd page, lol.