Why is the box in INCD to verify written data greyed out, im using my LG 4163B to write 3x DVD-RAM discs formatted in fat 32. I want bulletproof writing for backup purposes.

InCD 5, as you can see here:

http://www.nero.com/nero7/eng/Nero_InCD_5_Features.html

seems to fotmat only UDF files flavours, as version 4 did (the one I've, by the way). And it is a packet writing application.
FAT32 formatted DVD-RAM discs can be used without this kind of software - just drag and drop within Explorer.
RAM drivers are able to format FAT32 and UDF (at least 1.5 and 2.0) and allow you to write to disc directly, having ways to check data integrity. In this case you would not need InCD.

When you introduce InCD you probably will have not the drivers, that's why you see that greyed (pay attention, because the 2 of them may conflict)

If you use XP you get native support for DVD-RAM, but I don't know what kind of facilities it provides to you.

DVD-RAM does write/verify as part of the normal burn process. Burn errors or media defects should be corrected on the fly using drive firmware routines. If you use Panasonic's driver/utility package (available from various sources - links are in CDFreaks forums) you can format *standard UDF* with sector sparing for media defects. If you want even more bulletproof you can do a post burn followup compare using a tool such as DVDinfoPro etc. to catch the (normally extremely few) errors which may develop between your source and burner caused by such things as RF interference, bad cables and solar flares! FAT32, while convenient due to fairly easy portability, is slow and has many limitations compared to UDF and is generaly NOT recommended. Don't use InCD, DLA etc. with DVD-RAM! Just use the Panasonic drivers for Win32. Mac OSX does UDF native. I'm sure the various *NIX OS's do UDF with freely available drivers if not native.