http://www.visus.pt/mirrors/draytek/SmartMonitor/Software/V2.1.0/

works with win 7 and now authentication for 2820 works, according to pdf doc.
Gonna give it a go

Well it installs OK now on Win 7, but I cant get it to detect my 2820.

Do you have 64-bit Windows 7? Noticed it only supports 32-bit, according to the pdf.

it installs on 64 bit, thats what I have, ive tried 32 as well, makes no difference to detection for me.

Hi Chaps

I have installed on Win 7 32 and 64 bit but does not detect my 5510 router...

ANy advice?

Eventually got this working with my 2820, it needs to be used with a pc with dual network cards as the mirror port is only one way, and therefore traffic is monitored on the mirror card, and the authentication is done on the normal two-way card.
The downside so far is that it doesn't monitor any wireless traffic, which is a bit pointless really, I add a external wireless AP and it is fine, but defeats the purpose of the 2820 wireless really. Its a shame, but I'm getting there.