> one HUGE advantage that XM WX weather has over the other guys - real
> time weather as opposed to updates every 5 minutes like WSI.

WSI like Unisys is one of the three NEXRAD Information Dissemination
Service (NIDS) providers that has direct access to the WSR-88D hotline.
unlike http://www.wxworx.com/ who must buy from one the the three.

while the storm center checks each WSR-88D every min for new images, if
the radar is in clear air mode it takes around 10mins for it to publish
all its products..  in precipitation mode it spins faster and takes
about 5mins to publish all the products.  (there is also a severe
weather mode that some products are dropped.)
http://sysu1.wsicorp.com/unidata/intro.html

so while some mosaics are built every 5mins, it doesn't necessarily have
all new WSR-88D data as the each radar has different publish times.
http://weather.noaa.gov/monitor/radar/ plus both wsi and xm take over
15mins to download all their products, so what you see will ALWAYS be
old..

lots of your tax $$ and people make this work.  don't let some
clueless sales guy get away with a statement like that.
http://www.roc.noaa.gov/nnow.asp

now, the XM satalight is more powerful than the rented GE satalight WSI
uses, and I do like the XM mosaic, over the WSI one, so there are lots
things to compare, but delay isn't one of them.