you guys need to relax and if there is nothing worthwhile for you to contribute, maybe you should reply to threads that your posts will actually be useful. sheesh.
ok here we go:
keep the amd system BUT:
change processor to x2 3600 BRISBANE (which will be the 45nm one) heres the link:
dabs.com - AMD Athlon 64 X2 3600 AM2 1.9GHz (ADO3600DDBOX)
you can overclock it WELL past an x2 4800. mine can clock to almost 3.2ghz.
take the money left over like L35.00 or so i have no idea how much that is in dollars tho lol
and buy the 8800gts 320 that everyone is suggesting. it really is a better idea than sli'ing those two cards. now, i myself have sli 7900gs, and they kick some major arse. i would suggest that anything less than 7900gs in sli is not worth it. but, you said you want them to run dx10, so i guess that is a moot point.
so, i say the 8800gts 320, then if you really want sli, get another one later (the prices will drop pretty quickly i bet). 2 x 8800gts would be awesome, my friend.
the mobo i do not know anything about, so i have a hard time recommending it. it is compatible with the 4800 you have selected, and the 3600 i suggest, so you are okay there. i DO know that the 590 chipset is absolutely the best for am2 cpus (i have an evga 590 sli)
if you want to stick with wireless laser mouse, i suggest logitech g7. i have one, and it is the greatest thing in the history of mice. i didnt see it on your website, so you may have to look. it may put you over your budget, but i dunno...check it out.
i am also curious as to why you have a router? do you need it for your internet connection? your ISP will probably supply it if you do. even if not, a cheap-o netgear router can be had for 50 bucks U.S....once again no idea what that translates into for redcoat money lol.
make sure the ram you have and the ram you are purchasing run on the same voltage, or at least REALLY close. ie you do not want one stick to run at 2.2V and the other at 1.9V...that will cause you problems, most likely. make sure they will run within .1V of each other.
hope this helps, sorry about some of our other members hosin on ya about things and being RUDE.