After some investigation I decided to go for the Belkin N1 Wireless Modem Router at home. Compared to the vanilla (but VOIP) modem I purchased two years ago (another Belkin from iinet) when ADSL 2+ first came to Australia (F1PI241EGau) the new device is much lighter and has slick black finish and tron-like blue lights.
I hunted around for a simple freeware, network comparison tool. I settled on NetWorx and copied a video file from my media center (pretty static 4.1Mb per second transfer rate). After setting up the new modem (more options and therefore some playing) I found that I could transfer between 3.7 and 9.4Mbs from upto 10 meters away. Roughly is shortened a 350 Mb Heroes episode from 10 mins+ to 4 mins. The signal strength seems about double too. I get 5 bars in my lounge instead of 2 bars.
My worries additional radio in house (probably small), power consumption and interference with home phone etc. All in all N1 MIMO has been a good decision so far.
Wireless setup in Vista was a breeze (the security was great - firewall prevented access to machines until I explained what type of network to expect).
Update 23/2: I found that the standard 7.2 Atheros drivers were dropping the connection to the wireless router so I decided to update to Atheros AR5008X driver version 184.108.40.206 from here. So far so good.