computer won't boot after taking memory out

[bigunn]

I have an DELL Dimension 4500 that i tried to upgrade the memory in earlier today.  I got the memory in the mail, only after taking out the chip i had in the mobo, i realized i ordered the wrong memory.  So i stuck the old chip back in, but now it won't boot up.  I get power but can't get anything to transfer over to the monitor, and it also sounds almost as if the fans inside the comp are not working when i try and boot it up.

Any help or suggestions would be greatly appreciated

Bigunn

[patio]

Make sure the old RAM is seated properly...
Did you remove all power and take anti-static measures when doing the above ? ?

[bigunn]

old memory is seated right and i did have all the power off.   as far as anti static i dunno, it was a wood floored room, so figured i was fine.   Its just throwing me off why the internal fans aren't coming on either