I'm with AT&T and have an
N95-3. I tether via bluetooth (using windows dial up settings) and have maintained excellent high-speed connections for hours and hours. I'm not familiar with Walkinghotspot or JikuSpot.
One point however, I do find that my
N95 gets "flaky" when too many apps are running simultaneously in the background- you may want to ensure that everything is closed down and you're on a clean boot up before modeming.... just a thought. Good luck!