Why my CS1.6 fps so low?

The highest FPS i can achieved are 99..Not even more than 99...When sometime there are many corspe or any shooting effect, the fps will decrease to 40-60....And when come to smoke..i totaly cant play or shoot..the fps is 12!! WTH.. I already input all the fps config..even use game booster... My driver already updated... Is it my hard problem or .. The problem wif my windows?? And my disk are well defragmented.Sorry for broken english

Windows XP SP 3
1016MB RAM
Intel(R) Pentium(R) 4 CPU 3.06GHz
Intel(R) 82915G/GV/910GL Express Chipset Family
128.0 MB
May i noe is it my graphic card can't support?? Please reply me ASAP.. I nid ur help!! Thx!!!