HomeGroup, Play To, Network Sharing???

Okay, i'm new hear, and i've got a bunch of questions, they all really relate to the same thing:

My computer is running Windows 7 build 7100
My Brother's computer is aswell

We are both connected wirelessly to our Router/Modem (Livebox), and we are both connected to the same Homegroup (i finally managed to get them show up in Explorer), and we are both connected to WORKGROUP, as is my Dad (Vista) and our other PC (XP, wired to livebox for printer sharing).

So, i was trying to get the "Play To" feature in WMP to work with my brother and my computer, but it doesnt seem to work.

a) On my computer i can't select "Allow Remote control of my player" though i can on my Bro"s

b) In "Media Streaming Options" and "Show devices on Local Network"(default i can't see my brothers computer, and on his he can't see mine. (This is obviously the problem), but if i select "Show devices on all networks" we can see each others computers.
For some reason though, we can see our mums Kodak Photo Frame thing, and "Media Programs on this PC..."

c) In WMP on both our computers we cant see each others computers in the HomeGroup even though all media is shared, so we have to go and look in Explorer "Homegroup" - "XXX-PC" - Music


Please Help Me, and if you need more info on what i'm trying to get at, just ask and i will give it.
Thanks

yep im getting Server Busy too, i'll keep on checking back though
Thanks

Ive seen it working on Engadget aswell, i just cant figure out what is stopping me, and where did you get the RTM from? i take it isnt downloadable??

your first link is working, so i take a look.
But i already recreated the Homegroup, and IpV6 is enabled, but still nothing.

As in my screenshot, my PC being Benji-PC, and the one balcked out my brothers, you can see he is in the homegroup, and on the network, but in WMP i cant see his computer, just a media frame program on my dads pc

oh and as i said, on my PC i cant select "Allow Remote control of my player..." in WMP

i dont understand what you mean by "on the same subnet", and "all indexing" other than that everything is OK, i think, i mean i can view his files on my cpu and he can on mine.
Thanks