maybe there's something i forgot to tell. let's see:

i am using your build_fpc4nds.bat.
i have updated devkitpro with it's automated installer.
i am using the latest source of fpc (using the address from the batch-file)
and the latest libndsfpc.

directorys are:
d:\fpc for the fpc-source
d:\fpc4nds for youknowwhat
d:\arm-nds for binutils.

looking at the output when compiling fpc, there is no error, just a bunch
of warnings, for example something like tthread.inc is a stub and such.

my fpc.cfg, located in d:\fpc4nds\bin\arm-nds is:

-Tnds
-FuD:\fpc4nds\units\arm-nds
-XParm-nds-
-FDD:\fpc4nds
-FDD:\fpc4nds\bin\arm-nds
-FiD:\fpc4nds\libnds
-FlC:\devkitpro\libnds\lib
-FlC:\devkitpro\devkitARM\lib\gcc\arm-eabi\4.1.1
-FlC:\devkitpro\devkitARM\lib\gcc\arm-eabi\4.1.1\thumb
-FlC:\devkitpro\devkitARM\arm-eabi\lib
-FlC:\devkitpro\devkitARM\arm-eabi\lib\thumb

my batch-file for compiling arm9 is:

ppcarmnds %1.pp9 -Sg
@j:\nds\no$gba %1

... ppcarmnds is located in d:\fpc4nds\bin\arm-nds, which is included
in the path.

my batch-file for compiling arm9 and arm7 is

ppcarmnds %1.pp9 -Sg
ppcarmnds %1.pp7 -Sg
ndstool -c %1.nds -9 %1.arm9.bin -7 %1.arm7.bin
j:\nds\no$gba %1

PATH is:

PATH=c:\devkitPro\msys\bin;C:\WINDOWS\system32;C:\ WINDOWS;C:\WINDOWS\System32\Wb
em;C:\FPC214\bin\i386-Win32;D:\FPC4NDS\bin\arm-nds;c:\devkitpro\devkitarm\bin

... i have tried only with PATH=d:\fpc4nds\bin\arm-nds too.

oh, btw ... i can't compile the snow-demo you've made.
it says:

snow.pp(46,19) Error: Duplicate identifier "QRAN_SHIFT"
snow.pp(47,41) Error: Duplicate identifier "QRAN_MASK"
snow.pp(48,26) Error: Duplicate identifier "QRAN_MAX"
snow.pp(49,24) Error: Duplicate identifier "QRAN_A"
snow.pp(50,27) Error: Duplicate identifier "QRAN_C"
snow.pp(258,40) Error: Identifier not found "VRAM_A_MAIN_BG_0x6000000"
snow.pp(259,40) Error: Identifier not found "VRAM_B_MAIN_BG_0x6020000"
snow.pp(260,39) Error: Identifier not found "VRAM_C_SUB_BG_0x6200000"

maybe that give's you a clue. the converted 3d-examples you provided
did work properly (didn't test anything else yet).

i guess that's it. only thing i can try now is formating my hdd and
reinstalling XP ... sounds like a great idea xD