It's compatible, but unfortunately you only have a 300w PSU which is a bit too weak for that card. I recommend at least a good quality 350w PSU for that card.
You can still install the card, but playing games can cause your PC to crash, or worse... the PSU can become overwhelmed and overload. The best case scenario would be that only the PSU is destroyed. The absolute worse case would be if it causes a power surge and destroys all electronic components (rare, but it has happened). Or you might be somewhere in the middle with only a few components damaged so it will not be a total loss, but still expensive to replace.
The 9600GT was a good performing mainstream card back when it was new. Nowadays, it is considered to have "value oriented performance".