Installing gcc4.0.1 from sources for Debian

[muxec]

I downloaded gcc-core gcc and gcc-g++ from the official ftp. I configured it (as demended from upper level ./gcc/configure) than make (it wasted more than GB of disk) and finally make install

Says completed but if i gcc -v

muxec:/home/muxec/Downloads/gcc401# gcc -v
Reading specs from /usr/lib/gcc-lib/i486-linux/3.3.5/specs
Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/c++/3.3 --enable-shared --enable-__cxa_atexit --with-system-zlib --enable-nls --without-included-gettext --enable-clocale=gnu --enable-debug --enable-java-gc=boehm --enable-java-awt=xlib --enable-objc-gc i486-linux
Thread model: posix
gcc version 3.3.5 (Debian 1:3.3.5-13)

but else

muxec@muxec:~/SRP_DNA$ /home/muxec/Downloads/gcc401/gcc/xgcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ./gcc-4.0.1/configure  : (reconfigured) ./gcc-4.0.1/configure
Thread model: posix
gcc version 4.0.1

Why does not it recognize proper dirs?

HELP!!!!

Benchmarked gcc4.0.1. In my genetic algorithm benchmark program compiled with gcc4.0.1 performs 1.5% faster, than gcc3.3.5

[muxec]

OK, it's very odd.
Under root:
gcc -v
v3.3.5-debian
Under muxec(ordinary user)
gcc -v
v4.0.1
but
/usr/bin/gcc -v
v3.3.5-debian


So where is it? I do not want to search all PathDirs. And is it safe to copy the new executable to /usr/bin/ ?