Slow Wireless LAN in Leopard

Question

All right, I've spent the past 12 hours (on and off, of course) looking through all the threads in here, doing a lot of experimentation, and a bunch of clean installs and whatnots, and I've decided to start a new thread, since in many of the said threads, some people seemed to have similar issues, but the other issues in the same threads seem to be different problems, and it just becomes confusing when you try to trouble shoot something and people are talking about different problems.
So, this thread is specifically for people who satisfy these criteria under Leopard:
1) You're having issues with very slow file transfers in your *local network* when at least one end is connected wirelessly; that is to say, when both ends are connected to the router via ethernet, you see no problem at all.
2) Your wireless connection doesn't display problems when connecting to the internet.
3) It is not specifically an 802.11n issue; i.e., the problem can be duplicated when in Mixed b/g only mode and/or using an 802.11g router.
4) It's not a router connection issue; i.e., your wireless connection isn't being dropped, and you are able to find your AP and connect to it without any problems.
So basically, that more or less sums up my problem. My equipments:
MacBook Core2Duo 2.2GHz, 802.11b/g/n, OSX 10.5.2
iMac Core2Duo 2.13GHz, 802.11b/g/n, OSX 10.5.2
Router 1: TRENDnet TEW-631BRP (Draft N router), H/W V3.0R, FW v.1.0.3.7
Router 2: NETGEAR WGR614 v.5 (g), FW v.1.0.3_1.0.3
Internet: RCN Cable, 20Mbps/2Mbps
In my usual setup, the iMac is connected via Ethernet and the Macbook is connected wirelessly.
I know that this is a Leopard problem, but I'm not so sure it's a 10.5.2 specific problem. Let me explain.
I'd been using the TRENDnet more or less happily for the last couple of months. My iMac and Macbook have been in sync in terms of Leopard versions, so I know things were OK till last night when I first noticed problems. Transferring a large video file from the iMac to the Macbook would start off fine, then really slow down, and finally almost completely halt. Naturally, I blamed 10.5.2.
After trying all the different "fixes" in the Leopard/network related threads with no avail, I tried booting my laptop into Tiger (10.4.11) installed on an external HDD. Voila, wireless file transfer speed is fast at around 8MB/sec (obviously using N). I did a fresh install of 10.5, and the speed immediately dropped down to 1-2MB/sec, although not necessarily stalling. Then, updating to 10.5.2 slowed it down more, and now the transfers will sooner or later almost completely stall.
Again, I tried all the suggested remedies (use b/g Only mode, adjust RTS/Fragmentation thresholds, use WEP instead of WPA, delete all the Network Services in System Preferences -> Network, etc., etc.). Nothing helps. I tried swapping the router to an older Netgear (802.11g/b), and it's the same deal, so it's not a router issue.
A definite characteristic is that the transfer seems to stall after a certain period of sustained transferring; i.e., this will usually only happen when transferring large files (>200MB). If I were to download a folder with 600 JPEG files @ 1MB each, there won't be a problem, and the transfer rate will be pretty fast (although not as fast as under Tiger @ 7-8MB/sec), and it won't stall. It's only when I try to transfer big video files, etc., that this problem occurs.
If you are having similar issues, please share your experiences, suggest remedies, offer insights. I will try to answer any question you may have and that I may have missed to address.
PLEASE: if your symptoms are different from what's listed up there, please try to refrain from posting here, unless you are absolutely certain that the issues are related. Thanks.

Answer 1

I'll concur, network streaming since 10.5.X is painful at best and has gotten worse with every dot release. Apple, I've spent thousands of dollars on your equipment in the 13 years I've been using it and this is unacceptable.
Here's the home network for reference:
12MB uplink to Internet via Cox Cable --> brand new (yesterday) Airport Extreme (to replace a Linksys WRT 54G, which I had originally suspected was the culprit) 100MB Ethernet to Core 2 (single) Mac Mini. Media lives on a Lacie 500GB RAID1 array connected via Firewire 400. The Mini shares out to a Macbook Core 2 Duo @ 2GhZ, Airport Extreme and an iMac Core 2 Duo @ 2.16GhZ.
Movies stutter and die when streaming to the MacBook or the iMac, regardless of codec. The iTunes application can no longer stream mp3s from my shared library (on the Lacie array) to either of those two machines without constant rebuffering.
I have verified the Lacie array isn't suspect by copying known good (by test play on the Mini) files from it to the Desktop on the Mini and streaming from there. I've verified the MacBook and iMac aren't suspect by copying those same known good files to the Desktop on each and playing from there. I don't have issues opening a connection from one machine to any other on the network, but any sustained connection is an issue, regardless of networking protocol (AFP, SMB) or connection\authentication method (Finder sidebar or "Connect to Server" dialog.)
Apple, you have an obligation to your customers to resolve this. I've been a networking professional for 17 years and setting up the Airport Extreme was far from a challenge.