Quick answer, yes. but my setup is reversed. Dual tuner is in my xpmce machine and TV is stored there. Recorded TV is shared to the Vista Machine. 1st generation extender plays everything recorded on the xpmce machine as designed. Vista Machine and 2nd generation extender (Linksys DMA 2100) also will play everything recorded from the xpmce. The DMA2100 would be painfully slow (responding to remote commands) at times and eventually it became too much of a pain, so I stopped using it or watching recorded TV on the vista machine since it was in the same room as the XPMCE . Later I built a new xpmce 2005 machine (for more internal hard drive capacity) and never bothered to set it up for vista to be able to see it.
Fast forward a few months and my son gives me an evaluation copy of 7 ultimate. I load that on a new hard drive in the vista machine and just for grins set up media center in 7 to watch the xpmce hard drives for recorded TV. 7 found the DMA2100 extender and set it up for me. Then - It just worked! Recorded TV is found by the 7 machine and the DMA2100 extender works with a normal response time. The thumbnail pictures in 7 media center have not appeared although they used to when vista was getting them from the old xpmce machine. The only other thing that concerns me is the network usage by the 7 machine.