Networking Questions

I have a home network set up (I am a bit new to
networking) and everything is working but I have a question. I have certain
folders shared with the "downstairs" computer and certain folders shared
with the "upstairs" computer. The downstairs computer is running WinXP HE
with 1 G of DDR RAM and the upstairs computer is running WinME with 512 M of
SDRAM memory. The issues is this: I can see and have access to the
upstairs computer from the downstairs computer and I can see but NOT have
access to the downstairs computer from the upstairs computer...it says that
there is not enough memory. Is this truly the case or are there just
limitation with WinME that do not exist with WinXP HE?...or maybe I just
have something configured wrong. Before I go out
and buy more SDRAM memory or I upgrade WinME to WinXP HE...I would like know
for sure, if possible, which it is...Thanks for any advice you can
provide...

BTW...here is what I have...
OK...like a say, I am a bit new to this...what I have on the XP computer is:

Client for MS Networks
Eacfit Driver
File and Packet Sharing for MS Networks
QoS Packet
Internet Protocal

What I have on the ME computer is:

Client for MS Networks
LPR for TCP/IP printing
802.11g Wirless PCI card
Dial-up adpater
TCP/IP - 802.11g PCI Card
TCP/IP - Dial Up Adapter
File and Print Sharing for MS Networks

CP