Wider memory bus vs more RAM...?

[kirkwad]

Hi, my laptop and family desktop computer both have 512MB of RAM,
but the laptop has always been slower compared to the desktop when several programs are running at once.

And using everest i found out that the desktop has a 128-bit memory bus compared to the laptop's 64-bit bus.

I was thinking of upgrading the laptop's RAM to 1gig, but im wondering if this would even make much of a difference because it only has a 64-bit bus?

The laptop has a pentium4 3.2GHz with HT processor and the desktop is a 3.0GHz Pentium 4 with HT.

Any help would be appreciated,
thanks :U