slow internet for Macbook in clamshell mode after 10.5.3

You have to do the Archive and install to rollback. There are clues in your post about the "top open" but since the wifi antenna is in that lid it's almost assured you are bumping into "how things work."

I suggest that if you are using this laptop as some desktop you consider getting wired.
Bob

I had this question marked for reply and then, after a senior moment, forgot all about it.

With the lid down, the antenna is not in the optimal place for receiving signals from your wireless source. This is one of the reasons that the antenna is located in the lid and not in the base.

As Bob suggested, a wired connection would cure this problem.

Archive and Install is the usual way to rollback the OS but, if you are using Time Machine, there is an alternate method.

P

I have sitting on a shelf here a somewhat dated HP monitor with the older 4:3 aspect ratio, as I think it's called. Nice LCD, but the square shape kind of defeats the purpose of using it with a Mac. Nevertheless, with my DVI to VGA adapter, I have connected it to my MacBook Pro several times. But, never have I had any success in closing the lid while using an external monitor as the primary viewing screen. Now I haven't tackled that in awhile, and I think I missed something, but that's not my point. From my experience, MacBooks and their larger counterparts are not built to run as desktops.

I was always under the impression that you could never close a MacBook and use it with external peripherals successfully. But, according to this Apple document, you can. I've had poor luck with this, but it can be done, contrary to my original belief. Look at that and see if you're doing something wrong. Still, I say you should leave it open if it works better that way. As for the 5.3 update, WiFi connections have been working even better on my MacBook Pro, but each to their own.
The position of your MacBook may be the key as to why it doesn't perform as quickly when closed, as has been said above. The AirPort antenna is supposedly placed in the bezel of the computer, so you are basically moving it to a poor position and causing it to receive less, though that seems strange that a few inches/feet would cause such a dramatic loss.

The computer is going to wake up from your external devices if they are still plugged in. Now if you follow the Apple document instructions, you may be able to avoid this. If you are connecting the display to the MacBook before closing the lid, then that could be where the conflict is coming from. See the doc and try that to avoid more problems with it.
Hope that helps.

-BMF

i also own a macbook and a samsung syncmaster (the one that looks like their tv's do) but mine's 19". i don't use the macbook with the clamshell closed, but i find that as soon as i plug in the mini DVI cable to connect the monitor i lose my wifi signal almost entirely. the airport status even stays at 4 bars, but ftp transfers, browsing and email all struggle if they can even connect.

and then as soon as i unplug the monitor the transfers resume, pages load and emails start pouring in. i am at the opposite end of the house as the base station but there is a signal boosting antenna on the base station and works as long as i am not connected to the monitor.

i suspect it must be an issue with the samsung syncmaster monitors and not the clamshell being closed, or the antenna or macbook at all.