That one is an interesting mix of features. On the one hand, it has an external
power connector. (Usually a sign of slightly higher power consumption.)
The idea is, they wanted a source of +12V to run the power conversion,
without the limitations of the current carrying capabilities of the
pins on the AGP slot. On the other hand, the heatsink is passive (and
the heatsink is a bit larger than some of the other passively cooled
cards). I'd say this is a possible solution, as you don't plan to
use the 3D features, so it probably won't get that hot.

GIGABYTE GeForce 7600GS GV-N76G256D-RH Video Card
http://c1.neweggimages.com/NeweggImage/productimage/14-125-039-09.jpg

The 7600GS power varies between 14W and 28W or so, according to this
estimation (they used a 7600GT and downclocked it, to make the
measurement).

http://www.xbitlabs.com/articles/video/display/power-noise_6.html

You can read some of the review comments here. They mention the heatsink
runs pretty hot, so you may want to place a fan near the card. You can
connect a computer case fan to one of your motherboard fan headers, to get
a source of power for the fan.

http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16814125039

The second card (PV-T44A-WANG) is apparently carried by Dell. A non-Dell
web site lists the price as being somewhere in the $50 USD range. A couple
places list it as out of stock, but may be arriving soon. This site lists
the card for $42.

http://www.mwave.com/mwave/viewspec.hmx?scriteria=3903480

Judging by the size of the heatsink, the 6200 draws less power. Note that
the FX5200 AGP that I had a fan mounted next to, had the exact same kind
of heatsink as your 6200. So it still might need a fan, if there are
signs of instability.

If you can find the 6200 card for a reasonable price, then that might
run a bit cooler. If you don't want to deal with Internet sellers, then
get the 7600GS card. You'll need to provide a source of power to the 7600GS,
to the four pin Molex on the end of the card. If your power supply doesn't
have any spare Molex power connectors, you can use a "Y cable" to make
another connector for it. (Some video cards, like my ATI 9800Pro, included a
Y cable for power.) There is a female and two male connectors, and allows
extending power from the back of a disk drive. I've used quite a few
of these, for my computers, for one thing and another. I've also used
them to power fans.

http://c1.neweggimages.com/NeweggImage/productimage/12-201-006-02.jpg

The 7600GS won't use its maximum power, unless you are doing stuff
involving 3D. Games are something that uses 3D. Vista also does a
bit of 3D (Aero interface, compositing of windows etc). Perhaps an
application that uses OpenGL, would kick the card into 3D mode as
well.

Some video cards support user adjustment of core and memory clocks.
If you want to further reduce the power consumption of a card, then
turning down the clocks being used on the card, is one way to do it.

http://en.wikipedia.org/wiki/RivaTuner

In terms of installing the card, this is what I'd recommend.

1) Make sure you have a driver to install on the new card. There should
   be a CD in the box. You can also download a more recent driver from
   the Internet before you start work.
2) Uninstall the existing driver for the MX200. Check Add/Remove control
   panel, and look for the Nvidia driver.
3) Shut down and remove power from the computer. Change video cards.
4) On bootup, the new card will operate in a vanilla VGA mode.
   Install the new Nvidia driver. After a reboot, you should be offered
   more output resolutions, and be able to set up the display properly.
5) If the card runs too hot (either behaves unstable, or you burn yourself
   on the heatsink), then either you can experiment with Rivatuner or
   you can purchase a case cooling fan, and fit that next to the card,
   blowing on the heatsink.

If you need a fan, this is an example. I have one of the larger Vantec
fans, and it is pretty quiet. This one is 80mm square, and 27 CFM.
It is pictured with a Molex power connector, so if you purchased
yet another Molex Y cable, both this fan and the 7600GS power connector,
could run off an existing disk drive power cable.

http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16811999602

Finding a bracket to hold a fan, can actually be difficult. I made
my own bracket, using a piece of aluminum from the hardware store
(L shaped cross section). This is an example of a retail kit, that
could hold a fan where it is needed. This kit would allow positioning
a fan next to a video card (but takes up a slot or more).

http://www.logisyscomputer.com/viewsku.asp?SKUID=CF108&DID=COOLDEV
http://www.logisyscomputer.com/images/SKUImages/CF108_13.jpg   (picture)

There are also complete heatsink replacements for video cards, but
fitting cards that have an HSI bridge, is a bit more difficult. (Cooling
kits don't always fit AGP cards.) And the replacement coolers also make
your overall video card purchase a lot more expensive than it should be.
This is an example of one.

Here, someone is fitting a VF700 to their video card. The blue heatsink
covers the HSI chip. The problem with this, is the top edge of the
VF700, can bump into the side panel on the computer case. The video
card in this case, is a 6600GT AGP, a 50W card.

http://img163.imageshack.us/img163/9413/660029to.jpg

http://www.xbitlabs.com/articles/video/display/gpu-consumption2006_7.html

HTH,
   Paul