Haven't tried integrating yet (haven't seen any reports of successes/failures about that either). But I've tried to install it unattended on a clean Win2003 R2 Std install in VMWare, which doesn't have WGA stuff installed (who wants that crap on their server?) nor an internet connection. IE7 install fails! ie7.log says "IECUSTOM: Setup cannot continute because this system doesn't pass the Windows Genuine Advantage validation check. Please run the setup program again in attended mode.", and yes, this is on a 100% legit Win2003 copy! This is getting to be a royal PITA for everyone. If it wasn't for WGA, it would likely install just fine (no other errors of any kind in logs)
Sounds like I'll have to either integrate it (if it even works), bypass WGA altogether (I'm just NOT installing this spyware on a server - especially not for a crappy browser), or I'm stuck installing manually (repackaging as a last resort - no idea if there's a good old IEAK that doesn't do this nonsense). Thanks MS for making us go through this... Just f'n lovely.

Anyways. If you have (the latest?) WGA installed and have an internet connection, the switches I mentionned would likely work...
Edit: Integrating? You have to integrate from the original installer, the extracted ones won't do it. They say: "Extracted packages cannot be integrated. the /integrate switch must be used with the original software update package." How helpful of them to prevent that... And the /integrate switch doesn't work with the original setup seemingly (and there's a couple different ones). So there's likely no easy way to do this. They're preventing all possible ways to install, except the one where WGA fails on legit windows. Time to look at IEAK 7 I guess ... Hopefully it can produce some not totally braindead setups.
My last Western Digital drive is making weird noises and 3 partitions dropped. That can't be good

Edit2: IEAK 7 did it!

Switchless silent installer, no forced reboot, no need to install the WGA crap to get it to install, etc. Works great! Finally an installer that works (and you can set custom homepage to google.com and whatever you want, set max space for temp files, and lots of other good stuff) Haven't seen a way to disable the PhishingFilter there though, so registry tweak needed. Now all one needs to do is install
Multiple IE (with /silent or /verysilient) and one has all the standalone versions (3 to 6) along with their new v7 to test websites. Only Opera and Firefox left to install. If someone's too lazy to download IEAK to make their own IE7 installer for Win2003 SP1, I can upload it somewhere.