Problem with sound on my laptop :( HELP! Options

I have windows Vista Ultimate 32bit, intel core 2 laptop with 1GB Ram.

Now when I play a anything (mp3, youtube, whatever etc), sometimes the
sound just seems to "drag" and have a rough sound. Then it goes back
to normal.

It may do so once during a song/video/whatever, or may do so more than
once.

I tried under M$ drivers that Vista puts in and under propper realtek
drivers (from laptop's manufacturer's site) and it does the same
thing.

Note that I had tried another laptop the past week. First it had Home
Premium then I upgraded to Ultimate. In niether case did this problem
show itself (the laptop is gone now cause it had other problems).

Also, this laptop came with Home Premium and did not have this problem.
Then when I upgraded to Ultimate this problem happened

Is it a RAM isue? something else? Anyone know?