Lemme see if I got this straight. . .

Basically you want to hook your PS3 up to your computer
monitor ? I don't own a PS3 but right off the bat you
stated you have an older monitor. You indicated you wanted
to connect your PS3 to your video card ?

Means instantly it's probably lacking a digital interface.
( I don't recall any CRT with a DVI interface ) While there
are some monitors that will have the inputs for composite
signals, they are not very common.

The interface on your video card is output only No
input capability there. The other end of the cable connected
to your video card will need to be a monitor. Ps3 <-> DVI
port on video card will probably equal a lot of smoke.


So!

Unless your PS3 has the capability of composite output
I think you're better off going and getting that LCD
with a HDMI interface.

Sound will be the same issue unless the PS3 has both
optical / coax digital and standard stereo RCA jacks.
If optical / coax only, you'll need a receiver capable
of de-muxing it. If it does have RCA stereo jacks, then
easy to do. Cheap cable converter will do the trick there.
Or a speaker setup capable of multiple inputs with a
selector switch. I have a logitech setup that is like this
but is in the $500 range. :|