if you can could you quote in $AU of $US
Check Australian search engines like this and local large chain stores
for sales.
http://www.staticice.com.au/cgi-bin/search.cgi?q=xfx+6600gt
If you are talking 200 AU its around 148 US then the 6600GT is the
obvious choice. However the prices given in AU here are kind of high.
In the US there are versions as low as $100US with rebates.
Youll probably be jazzed by a 6600GT. I have the 400mx too and its
ANCIENT. Its actually quite decent for an older PC which is used only
to surf the web and do wordprocessing but its beyond useless for
modern gaming. The specs they give on that as a min are a joke.
One thing you have a pretty wimpy PC processor too. I know cause I
have a 1600 AMD athlon sitting around which Ive tested with a 9600XT.
The 6600GT is much better than that card but its not a bad card and
its really marginal with a 1600. Combine that with one of my more
modern PCs 3200 AMD 64 and it works a lot better.
You dont need a super powerful PC or the most expensive card but you
dont want a horrible deficit in either area or you have to make up for
it more with the other. With my 1600 Athlon there was a fair
difference when I swapped out a plain old 9600 with a 9600XT on it
which surprised me. The 9600 works ok though with lower settings with
the 3200 AMD.
After a certain point though unless you want to really crank up the
resolution and effects it doesnt make as much difference. I bought a
X2 dual core 3800 and a 7800GT OC BFG thinking WOWEE another
substantial difference and frankly I dont notice that much at all from
my 3000 AMD 64 and 800XL which I used to have. Im sure I have far more
reserve power for when future games come out though.