Can I play Battlefield 2 using a nVIDIA GForce 7300 GT (256MB) ?

I have a Intel Pentium 4 CPU: 2.4 Ghz RAM: 1 Gb and lots of hard drive space. I looked at the supporting video cards at gamespy but I believe mine is newer than those.

Yes of course. The official requirement states at least a FX5700 (could be minimum). The FX5700 has a core clock of only 425mhz and memclock of 600mhz and 4 pixel pipelines. The 7300GT dd3 usually has 500/1200mhz clocks and 8 pipelines.

yes you can play that game with no problem

set up your graphics card as it should be setup. use windows dirctx diagnostic to see if it is tuned up right

Simply put, yes you can and it should run fine.