Slow File Sharing over Wireless Connection?

Setup
XP Pro SP2 Laptop – Wireless (WEP 128bit key), excelent signal strengh – 54mps
XP Home SP2 Desktop – Hardwire to 604T
I have a DLink G604T wireless adsl router. Using DHCP from the G604T.

Browsing the web is fine – both wired and wireless, incluing VPN access to my workplaces intranet.

However when browsing shared files from the desktop, I get 30 second ‘lags’ – simply addressing the desktop via explorer EG \\destktop – it can take upto 30 secons to show a list of 3 network shared directories.