Datacolor User to User Support Group.

Hi
found this great group...and have already a problem and question - and hope for help.
I "upraded" to a dual monitor system with a new graphic card and an additional monitor. I managed to calibrate the 2 monitors with spyder 2. it works, but unfortunately my images on the 2 monitors look very very different. One which I hope i can trust, my old Dell 2007 looks very "pale", warm and dark compared to my new monitor the HP LP24sw that is brighter, colder and extremly saturated.
what can I do? which one to trust?
I am a bit lost, since I hoped for an improvement with 2 monitors and now I have none to trust anymore :(
Would appreciate some help.
Phil