Wireless speed completely different to Ethernet speed.

[#1]

Hello all.
Bit confused. Basically my router  is connected to my desktop via the ethernet cable and is fine - getting speeds of anything up to 12megs.
But on my laptop and iPhone through wifi I dont seem to get more than 1.5 megs, and sometimes as low as 0.06mbps. Is there any reason for such a discrepancy?
Tried calling the support line, but they seem a little busy at the mo.
Cheers for any tips/advice.
Luke

[#2]

What speed does the laptop say it has connected to the router at?
Is the router configured for 802.11g or 802.11b?
Have you tried different channels (try 1, 6 or 11)?
Is the router MTU set to 1500?

[#3]

If the laptop doesn't say the speed it's connected to the router at, it should at least give you a signal strength. Try the different channels as Jelv suggested, the 3 he's given are good ones as they are spaced well apart.

[#4]

not sure if this is of interest, i had the same problem with my new wireless router and i changed the chanel to 13 after running netstumbler and found the strongest signal which was my neighbour was also on ch.8. its fine now. i also ran the tcp optimizer program which improved my wireless speed but made my ethernet speed on my pc worse but it rolled back the settings ok using the back up file it creates prior to making any changes but as it changes registry values i would proceed with caution
interesting info regarding chanels
http://www.broadbandspeedchecker.co.uk/guides/improve_wireless_internet_speed.aspx