As already mentioned Xenosaga 1 really needs a powerful CPU to work. GSDX DirectX10 helps a lot too, but even with that and some speedhacks you will encounter slow spots.
I am afraid short of buying Vista and / or a new CPU you won't be able to improve speed very much.
VU skip remedies the situation a little bit ( try 2-2 or 4-4 settings ) but makes playing the game not as much fun as using your PS2.
EDIT:
Xenosaga 1-3 are playable though. I played through all of them with PCSX2.
I am afraid short of buying Vista and / or a new CPU you won't be able to improve speed very much.
VU skip remedies the situation a little bit ( try 2-2 or 4-4 settings ) but makes playing the game not as much fun as using your PS2.
EDIT:
Xenosaga 1-3 are playable though. I played through all of them with PCSX2.
Reading the OFFICAL GUIDE can answer 90% of your newbie questions
SEARCHING the forums can answer 90% of your advanced questions.
SEARCHING the forums can answer 90% of your advanced questions.