Connecting Older Smartphone to local network to surf internet.

There was a good deal on the Treo 300 Smartphones and since I've never
owned a PDA, I thought I'd buy one.
I haven't received it yet but started to look at the manual from the
internet.
My question is, can I surf the internet, using this smartphone and a LAN
or wireless LAN? I know it is not as good as a laptop or desktop but
there may be instances when you have access to a free Wi-Fi hotspot and
want to waste some time or check your email.
This smartphone can apparently surf the net if you pay a subscription
fee to Sprint but I'm not interested in using Sprint.
Would a USB Wireless Adapter work? I assume you would need the correct
driver/software.