First your link about this model.
Ok the issue is WELL DISCUSSED and I no longer write about drivers and more on old laptops. You can reload the OS without me writing why it rarely fixes it. Let me share what our shop does.
1. Disable and even remove the wifi mini pci card.
2. Slip in some under 20 buck wifi pc-card like http://www.geeks.com/details.asp?invtid=F5D9010&cat=NET (there are hundreds to choose from)
3. Install the drivers and watch it work better.
There are too many lost days of drivers and even replacing the internal card that I no longer advise or do that. It's not worth the chance it may not pay off.
I have a 5 year old HP Pavillion zd8205 laptop running XP Pro, P4 2.8 Ghz, 2Gig Ram, 400Mhz FSB . I have a wired / wireless home network with DSL. My wired desktop has DL speeds of 1294 Kbs & uploads at 217 Kbs. My son's laptop has similar speeds. But my HP which has similar speeds wirelessly is just like dial-up. It reminds me of my old Packard Bell without the background hiss. I have tried tweaking various settings and even foolishly paid for a software program (Activespeed Speed Booster) The pages take forever to load and when the progress indicator bar fills completely nothing happens for SEVERAL seconds then half the page pops and the next portion begins to load, The whole time the hard drive is humming away. What am I missing? Is it the computer?