Wired & Wireless

I have a wired home network that works well. I bought a
laptop and successfully wired it into the network -- both
Internet access and file sharing. I also bought a Belkin
wireless card and a Belkin wireless router (setup to
serve as an access point only). When using the wireless
connection, I can access the Internet, but now the laptop
cannot see or be seen by the other computers on the
network. I get a security violation in both directions.
Is there a way to set this up to be able to go seamlessly
between wired and wireless? How do I make this work at
all?
The laptop runs XP home. Other computers on the network
run XP Pro or Win 98 SE.
Thanks!