Ping is fast, file sharing over IP is slow. Why?

Cheers!

Why can 98 use XP:s files fast, but the other way around is slow?

Simple network:

98: oldish computer with standard Windows 98 and an ethernet card
connected to Netgear router/gateway/ADSL
XP: newish laptop with updated XP connected wireless to the Netgear
thing. In addition it used to be connected to the Internet through a
56k modem. (Are there old routes in there that has to be deleted?)

Situation:
- XP can ping 98 and is fast, 3-5 ms.
- 98 can ping XP and is fast, 3-5 ms.
- 98 and XP both show up in the network neighbourhood window on both
machines.
- 98 can use XP:s shared files without any problem or performance
trouble.
- XP can use 98:s files, but there seem to be some kind of timeout
sitaution: it works but can take 20-30 s before activity begins, for
instance showing a property of a 98 file.
- I *think* I am using netbios over IP on both machines.
- XP hostname is 6 characters, no special chars, 98:s is 10
characters, no specials.

I am rahter fluent around systems like these, and know TCP/IP routing
quite well. Windows networking, however, is new to me.

So, how come 98 can use XP:s files fast, but the other way around is
slow?

Any help on this matter would be most welcome!

Per Stromgren.