frostlp,
the blowing snow is a bit tricky to install and I'll give you a step by step here and perhaps it will help others when they get to that installation.
Some quick history the effect is from the FS9 SIRP scenery modified to work within FSX.
INSTALLATION PROCESS:
1. Download the blowing_snow_effect.zip and extract it to a temporary folder.
2. It creates a blowing_snow_effects folder containing two additional .zip files, and two informational .jpg files that are not needed.
3. Unzip the cirp_blowing_snow_efx.zip file creating a cirp_blowing_snow_efx folder. It contains another folder named CIRP Blowing Snow EFX with a scenery sub-folder with the .bgl files for each Ice Station. (again the jpg's are for information only)
4. This CIRP Blowing Snow EFX is the folder that is added to your FSX Addon Scenery folder or wherever you place your CIRP files as you have already done.
5. Now unzip the remaining SIRP_EZ_Effects.zip creating a folder named SIRP_EZ_Effects containing two more folders and the SIRP EZ Effects Manual.pdf.
6. All the fx_SIRP files in the Effects folder are placed into the FSX\Effects folder. There is also a texture sub-folder. The files in the texture sub-folder are placed in the FSX\Effects\texture folder.
7. The last folder in the SIRP_EZ_Effects is named EZ Library BGL and has a scenery sub-folder in it.
There are two file in this sub-folder, sirp_ez_effects.bgl and sirp_ez_effects.txt. Just copy those two files into your EZ Scenery Library\scenery sub-folder.
Now cross your ankles, face NSW count to 1000 nod three times and spit downwind. Start FSX and watch the snow blow. As you already know you have to have some wind in the sim or it will not blow.
PS: When the blowing snow was developed for SIRP for FS2004 Acceleration was not even thought of so it is not a requirement for the effect to work in FSX either.