Originally Posted by punkymanification

So I had the same issues as described in my 2004 Accord, 4cyl ex, had vibration at both 40 & 60 mph only on acceleration. What I did to FIX the issue was first, replace both half shaft/axels. Many talk about doing just the left side, do both there cheap $80 Pass $70 Driver, just make sure they are new and not rebuilt, you don't need to get them from honda just your local parts store. They are also pretty easy to install. There was no visible wear on either shaft, but they were one of the causes of the vibration. At first I only replaced the left and still had the vibration so that is why I did both. Next, I replaced three of four motor mounts. The two side mounts were trashed and the front was boarder line. Honda is very proud of these mounts, they wanted $457 for just the front & back not including the two side mounts. So I bought 4 after market mounts, two from O'Reilly's which were the two side mounts, and the front and back were from Amazon, the DEA brand. I will caution you, if you read the threads there is some mention of the (DEA)mounts not being the same height. I did not have that specific experience with them, but when I installed the back it gave me fits just to get it threaded on. Then once I had it bolted down it created another vibration that was bad on idle and worse when the A/C was on. So I used the old rear mount as it seemed to be ok, when placed back in position there were no more vibrations at idle or with the a/c on. I had no issues with either of the side mounts or front mount. If I was going to replace the rear mount, I would get the OEM from Honda, though be prepared to pay up and call around to local honda shops in your area for the best price.
Replacing the mounts on the 4cyl is not hard either, though it does help to have a 1/2in drive and get yourself and swivle socket and long extension to help make some of the tough angles. You should not have to remove any hoses on the 4cyl though I did have to remove the battery and housing to get to one of the side mounts as well as pull the break fluid reservoir off its clip. You are also going to need a jack, jack stands and a 2x4 to take the pressure off the mounts. I also suggest putting a little light grease on the bolts when putting them back as it makes them go in a bit easier.
Making the above repairs solved all the vibration issues, good luck and I hope this helps!