Installed windows 7 Rtm on Amilo PA 3553. no problems.
Just do some research and the drivers are all available.
1, Back your drivers, I reccommend Driver genius pro 2009 utillity software.
2, Driver Folder on C Drive save and back up. You will need to install Launch manager after upgrade
3, Update Your Graphics card, ATI Radeon mobility HD 3470 Hybrid x 2 With,
ATI Support, OS Windows 7. Look for Windows 7 beta release 32 or 64 bit.
Install or save. This release takes care of both HD 3470 and HD 3200
5, Update your AMD Raid from ATI,
This is where I used Driver genius pro 2009, (small price to pay). Run program and update drivers for Windows 7 only. This will find all your AMD ATI Related chipset Drivers, Realtek, JMmicro card reader etc etc.
To be honest Driver Genius found the lot.
6, Do Not Upgrade to Windows 7, Use custom Install and do a clean install. This moves your operating system to Windows.old ( you can delete afterwards) Do not Format the System Recovery Reseverd at the begining of your Hard Drive.Windows 7 will automatically highlight where it will be installed.
7, After New Install of Windows 7, Fn + F1 to enable Atheros wireless card will not work, so go to the Drivers folder you saved from your C Drive, Open, then open Software, Open Launch PA folder and install the launch manager.
Now you can enable your wireless card.
Windows 7 update takes care of everything else including updates to your ATI radeon mobility HD3470 and the HD3200.
8, Realtek updates I recommend do it yourself.
9, For the HDMI, Install ATI HDMI drivers from ATI Support( Better driver in my opinion)
I Do hope this helps, I have encountered One Issue, NORTON 360.
NORTON SUPPORT has a patch update to v3, then updates your entire NORTON 360, issues resolved,
I Hope this helps to many out there who have a Amilo PA 3553, New computer now, quicker, easier, less cpu , Best OS Scince Win 98/XP