Please Please Please Help! New Mac User... Options

[briziofa]

hello everyone,

i'm a new forum member, i'm sorry for my bad english but i'm italian... :-)

a week ago i decided to buy a new computer, and i choose a new macbook 13" with intel core duo processor.
I had been using pc for 10 years and it's my first mac now.
I used pc for producing and djing with programs like ableton live and fruity loops, and i own a two-months old TASCAM us-122L external sound card. It worked good with pc.

Here's my HUGE problems:
I couldn't make anything work!!!

1- I installed live 5.0 for mac os and it has got two problems:
-i couldn't play my live file, the CPU usage goes up till 90-100% and the sound gets weird and distorted. never happened with my previous pc, AMD athlon 1200 mhz with 256 Ram
-my soundcard can't be selected as sound device in the preferences, only built-in audio shows up as option, although i installed all newest drivers and firmware from tascam site. The card works good with i-tunes and garageband.

I updated all the mac software and firmware, i got osx tiger latest version.

2- There's no fl studio for mac, so i installed boot camp, latest version and win xp. it runs ok and i installed my version of fruity loops. another problem.
if i choose us-122 as audio device, sound gets soon distorted, it slowdown and the buffer underruns counter grows up till 400 (!!). There's no buffer or latency setting that makes it better. If i choose built-in audio device, it starts to be clipping only after 40 seconds, and then every 15-30 secs. the cpu usage is always 1-2%.

When i close fruity, strange clipping noises come from the speakers.

I tried to install all newest drivers for everything, and i also installed from windows update download center the dual core speed patch. nothing's better. I also tried ASIO drivers.
Both in Mac OS and Win XP i turned off all energy saving programs and set all performance settings to the top.

I'm getting crazy. I will destroy this mac if the things won't be better.