Query - Power limitation

Archived from groups: microsoft.public.windowsxp.basics (More info?)

Mp PC is a (German) Targa, Athlon 1.533 (1800+) processor, 3 years old,
originally running XPhome.
Supplied kit was - 40GB hdd, 256Mb RAM, 56K modem, DVD ROM, CD-RW, 6 x USB1
ports, on-board sound chip.
Upgrades - added another 512MB RAM, Soundblaster Audigy sound card, USB2 2
port card, second 40GB hdd. Removed 56K modem, installed 2 x LAN cards, one
for cable modem, the other for network to notebook. Am now running XPPro,
with SP2 and later upgrades all installed.

I have a 4 port USB2 hub with its own power supply (and it lights up, so
selfpower is working). Also have a 256Mb USB2 memory stick.
PROBLEM - memory stick works as USB2 only in the actual port on the card.
If I connect the 4 port hub, then insert the memory stick into a hub port,
error message "insufficient power" comes on, the stick is not recognised.
There are no other USB devices connected.

According to Device Manager, everything is working, no conflicts. Ditto -
Belarc.

Is this possibly insufficient PSU power (am I really running at the outer
limit?) Unfortunately I cannot say what its rated power is, there's no
visible label, either on tower case rear, or on the actual PSU. Odd, but
true. Hence, I'm guessing - would like yr opinions.