If your board doesn't have auto reset, then you would have to have pressed the reset button manually to upload a sketch. If you did then what d450 is saying is that new chips have newer bootloaders and the 'window' for pressing reset during the upload process is much narrower and difficult to get right. If you didn't have to press reset to get sketches to upload then the board has auto reset and its not applicable.
I always push reset before uploading, mostly about 5-10 seconds before hitting the upload button. I understand about that "window" now, so I'll try with different amount of seconds (-1 to 10) between resetting and uploading.....
.... and
it is not working, i get a red led that goes on and stays on, program says its uploading but it should be done in minutes, not in hours, right?
so this autoresethack is that something i can do myself?
I do uploads without the benefit of the auto reset feature. Here's my technique:
First: I have a Duemilanove with the FTDI chip removed (fried it). I'm using the SparkFun FTDI breakout to upload to the board.
The IDE will compile the code and then upload to the board. At the moment the upload starts, the send/recv LEDs on the board will blink once very fast and not very bright. If you press reset within about 1 sec of that blink, it will upload successfully.
If you press too soon, the bootloader continues on and no longer accepts serial data from the IDE.
If you press too late, the upload function gives up on the board.
@koyaanisqatsi
FWIW it's even easier with the the newer IDE (0017). You can push Reset as soon as the ~ Compiled Successfully ~ line appears in the status area. Works every time and your less likely to go cross eyed. 
Do these run at the same clock speed? Are there any differences in pinout between the two chips?
I'm not familiar with these boards but there might be components that need changed to support the new chip?
The basics of what the chip needs should be listed in this standalone tutorial, maybe make sure your board uses similar values:
the 328 and the 168 are quite compatible. if one works the other should.
the bootloader/reset issue seems like the most important issue. a new bootloader will not wait 10 seconds for your upload.
if you are using the 017 or 018 ide, click the upload button, wait for the "xxx bytes" message, and THEN push reset on your board. try this a few times. you may want to look into an auto-reset mod if possible with your board - where did you buy it?
Yes!!!
that last post did the trick!
this is great
just wait till the xxxxbytes sign, and then push reset!
hahaha
it can be so simple!