Dan, the suggestions already posted carry the weight of solid experience. That said, I'd like to offer my [i]two bits[/i] for what it's worth.
1) I have used both USB and PC card wireless adapters. My experience is the opposite of the last two posters - USB adapters work better.
2) Netgear makes the worst wireless equipment on the planet. My Netgear cable modem actually burned up within a few months of purchase, and their technical support was worse than worthless.
3) Linksys configurations are stable and their hardware is inexpensive. The previous postings suggest little difference in performance, but I have found otherwise. My Linksys router/adapter have performed perfectly for two years without incident.
4) Consider disabling encryption. The security folks will jump all over me for this recommendation, but I have found encryption to slow connections and to be associated with dropped connections. Transfer rates are significantly slower with encryption enabled. WPA is more troublesome than WEP, and as you know, WEP is less secure than WPA.
5) I have no [i]intruders[/i] in my wireless network with encryption disabled. I can monitor this with the Linksys configuration menu:
Status > Local Network > DHCP Client Table
I have never seen an unauthorized MAC address on my network, and my SSID is always broadcast.
6) If you are willing to take the risk of disabling encryption, you can [i]filter[/i] the MAC addresses authorized on the network. Normally these will be the MAC addresses of the wireless adapters, or the desktop computer's native MAC address if it's connected by Ethernet cable to the router.
7) A vertical booster antenna on the router can expand [i]horizontal[/i] range by ~50%.
8) Look for 2.4GHz interference, particularly from cordless telephone base stations.
9) Consider bandwidth issues if there are other channels with >30% signal strength. There should be 5 channels between your router and the competing signal.
10) Look for RF interference (fans, motors, hard drives, etc.)
11) Look for shielding issues (metal cabinets, etc).
12) The following hardware has worked seamlessly for me:
http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1115416825655&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=2565536001B17
http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1154470123093&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=2309339789B07
That about exhausts my knowledge of wireless connection glitches. I hope it may be useful for you. Good luck.
Rick/Portland, OR