Ok, some clean up and updates.
for E155X, there is firmware and software
Firmware: (I don't think there is DiGi custom firmware, DiGi just uses HuaWei's firmware)
11.608.13.01.00.B409 (5.6MB)11.608.14.15.311.B418 (6.3MB)11.609.18.00.00.B418 (6.6MB) (This is what I am currently using without problems)
Software: (This updates the software installer in the modem's ROM, I don't remember which one is DiGi's)
UTPS11.300.05.06.311_MAC11.303.08.02.311 (14.8MB)UTPS11.300.05.08.311_MAC11.303.08.03.311 (14.7MB)UTPS11.300.13.00.03_MAC11.301.06.00.03 (20.4MB)UTPS11.302.09.00.03_MAC11.301.10.00.03 (19.6MB) (This is what I am currently using without problems)
Unlocker: (Some of the updates require a Flashing Password, key in your modem's IMEI to generate the password)
v4mpire_unlocker (261KB) (This software has other functions too, claims to be able to unlock vodaphone phones, ZTE and HuaWei modems)
Files are archived in 7z, LZMA2 compression.
For WinRAR or 7-Zip, you will need at least WinRAR 3.91, 7-Zip 9.04 to extract.
(since flashing could only be done in Windows, so I guess it would be moot to put up any Mac or *nix compatible extractors)
There is no recommended version of firmware or software, each have their own pro and cons.
Different ppl may want/need different features and everybody uses the Internet differently.
So best way is to play around with them and use which ever suits you best.
Difference between DiGi and HuaWei firmware?
More options I guess, and less the DiGi branding.
You can reflash the firmware and play around and use the one that works best for you.
I'm currently using this modem with DiGi Prepaid Broadband, on Macbook 4,2 running Mac OS 10.6, mainly for file downloads. I do the flashing in Windows 2005.
So I would not be able to relate to any Vista/7/x64/Facebook problems.
Regarding Google's warning about my site:
There are many sites getting false positives from Google, unfortunately mine was (and still is) one of them.
Not to worry cause you won't be browsing the site (unless you want to), you will just be grabbing binary files from direct download links.