Sounds as if you are not getting good wireless reception. If your computer is too far away from the router or if there are a number of obstacles in between, it can significantly degrade the wireless signal.
Also, if your wireless router is 802.11G it may be broadcasting both a wireless G and B signal which also slows down performance a bit.

First, try moving your computer close to the router to see if speed improves...just as a test.

Here are some things you could do to improve reception and transmission speeds:

- Make sure your computer is not too far away from the router/AP
- Try to position your computer so it is blocked by the least number of obstacles.
- Check the control panel for your router and make sure it is broadcasting at maximum strength.
- If your desktop and the laptop have wireless G cards and your router is wireless G compatible, disable the wireless B signal. (set it to wireless G only)
- Disable WEP and WPA unless you absolutely need them (since they degrade performance). Use MAC address filtering instead.

Hope you have good luck getting the wireless network working better.