CURRENT STATUS:
PC Suite installs and works (needs small installation workaround, see below)
NSU installs but doesn't work (see below for explanation)
Ovi Suite 1.1 installs and works (except bundled NSU, which is the same as separately distributed one)
Ovi Suite 2.0 BETA installs and works (except software updates)

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If you wish to install Nokia PC Suite on Windows Server 2008 R2, you should do the following:

1. Download Nokia PC Suite (I tried version 7.1.30.9).
The latest version may be found here.
2. Right click at the downloaded file and in the contextmenu choose Properties, then go to Compatibility tab and click Change settings for all users (if you're not logged in as Admin)
3. Set Run this program in compatibility mode for: -> Windows XP (Service Pack 2) and check Run this program as an administrator.
4. Click OK on both windows and run the installer.
5. Nokia PC Suite should install now, but the Get Connected wizard won't work for an unknown reason. Instead of using it, just set your phone's USB connection mode to PC Suite and plug it in the PC. Let Windows install all additional drivers automatically, you may be prompted to reboot after installation completes.
6. Nokia PC Suite is now ready![/color]
Note: I haven't been able to test either IR or Bluetooth connections. They may or may not work. Please post here if you have any info.

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NSU can be installed but doesn't work (I tried version 1.7.3, fails to find the device, see attached screenshot), if you manage to make it work, please post here.

If you still want to install NSU, you may find the latest version here.
You will need to do the same compatibility mode trick as with the PC Suite (see above).
Please let me know if NSU works on your R2!

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Nokia Ovi Suite 1.1 installs and works without any quirks, but it contains the same NSU so updates don't work either.
>Download here.

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Nokia Ovi Suite 2.0 BETA installs and works except (yet again!) software updating. This time it manages to actually download the firmware file but shows some kind of "Internal error" at the beginning of installation (screenshot later).
>Download here.

Does the workaround for Windows Server 2008 work for you?

viewtopic.php?f=8&t=468

Yes, it helped, thank you!

P.S. I have updated the first post to reflect the current status. There seem to be some issues with NSU.

An update:

I reinstalled everything 2 times and installed in different order but still didn't succeed to make NSU work.

Then I accidentially discovered that Nokia has a new Suite called Ovi Suite which is meant to be a replacement to PC Suite. I downloaded v1.1 and installed it only to discover that it contains the very same NSU (actually even an older version which automatically updates itself upon first execution).

After this I (yet again) accidentially discovered that they also have a new Ovi Suite 2.0 BETA which is rewritten from scratch. It has a new built-in updater which succeeds to run but fails to update with a critical error (screenshot later).

Still struggling...