Hello macthenite1_ECG,
Hope this reply does not come too late.
The LabVIEW Advanced SIgnal Processing Toolset has VIs (also an Express VI) that allows you to view the PSD calculated using AR method. Many other methods like Periodogram, ARMA, MUSIC and Welch are also supported. You can find more details at - http://sine.ni.com/nips/cds/view/p/lang/en/nid/1395.
Hope this helps!
Regards,
Abhishek