[teilhardo]

Hi Yukon,
Check the voltage running from your parallel port. Is it >3 volts?
As far as I know, most computers use the CMOS standard 5 volts. The resistor that you attach shouldn't effect the voltage, just the current. In otherwords:

PPort _____________
(+5V) ------\/\/\/\/---------|+5Vin
300ohm |
| Relay
|
Ground ---------------------| 0V in
(0V) |_____________

if you only get 2.9 volts, you'll have to get a relay with a lower Vin value.
I hope this works

-Tei