graphics card for P2.4Mhz? Radeon 9600XT or Geforce 6600TD?

I am running Fs2004 on a three year old P42.4Mhz with 512MB ram and a 64MB Gf4Mx440 graphics card. As FsX will arrive only in a year I have decided to upgrade a bit my old computer a bit by adding 512MB of ram and also a new and cheap 128MB video-card (90-110euro). So I have made some research on the Internet and I am hesitating now between the Radeon 9600Xt(95 euro) and an Geforce 6600TD(110 euro) which should both almost double my frame-rate, if I believe what I have read.Which one is the better card for FS2004? Ande very important, as I am no specialist, are those cards easy to install? Do they need a special power-supply ?Thanks in advance. Guy