you should stop trying to use those speakers on your laptop NOW, if the impedance is too low/high you will burn out your output stage on the soundcard, just buy some cheap powered speakers (£10 or less on the market), far cheaper than either getting your laptop repaired or replaced.
NOTE: electronics is my hobby, I must stress you are running a risk of destroying your audio output stage, do not just wire anything up to a amplifier and expect it to work, most amplifier outputs are matched to the speakers, too low an impedance is like a short, it will burn stuff out, too high a resistance will make for weak sound and the amp will have to run full power, again risking a blowup, thats the reason many sound systems have warnings about the correct speakers being used plastered on the back, modern circuits are tolerant and can operate over a wide range, but costs cut corners and you can`t be sure your laptop maker didn`t cut corners, you should expect something like that, I mean do you realy think the makers built it to run some 3ft tall speakers as well as an in-ear set of headphones?, just get a set of cheap powered speakers, much safer for your laptop and your wallet, why do you think powered speakers have the
powered bit? to save current drain on the soundcard since the speakers could draw more than the card could supply on it`s own safely.
Mentor.
PC1: P4 hyperthreading 3ghz, 1gig mem, 2x160gig hd`s, ATI radeon 9800 pro gfx, 6 way surround sound, PC2: AMD 1.2ghz, 512mb ram, FX5200 ultra gfx, stereo 16 bit soundblaster, ups.