since you are using slackware (wise choice - i love it as well ), you can either use the tgz from linuxpackages
http://www.linuxpackages.net/search_view.php?by=name&name=virtual&ver=

or add the package from your distro repository via slapt-get/gslapt

the 64bit mod may be the reason for your problems though. i only use slack 32.

ill give it a try the documentation said no gcc in 4.0 series but ill try the slack package it isntalls the same on slamd64,,,thanks a lot i will keep you posted

Warning: gcc version mismatch! Rebuilding vboxdrv.ko is recommended
Warning: kernel version mismatch! Rebuilding vboxdrv.ko is recommended

ya figured as much hmn rebuild vboxdrv.. sounds like a challenge.. a scarey challenge lol

kernel version mismatch - feels like it doesn't like the 64bit mod. never forget that slamd64 is an inofficial port of slack. try installpkg -q <packet> to mute the warning messages.

otherwise build it (the whole application) from source. the source is available as well as build instructions from the virtualbox website. it's customized for debian though, but it's a pretty much standard compilation with ./configure, make and make install.

if you can't get virtualbox to work, try QEMU, Bochs or Xen (though i have no experience with them).

it installed alright lol thats the run error ya im thinking its the 64 bit port of slackware, not to mention 4.0++ gcc version
Prerequisites

You need:
GCC 3.2.3 or later (except for the GCC 4.0.x series)
this was in the technical info.. on the documentation

gcc -v
Reading specs from /usr/lib64/gcc/x86_64-slamd64-linux/4.1.2/specs
Target: x86_64-slamd64-linux
Configured with: ../gcc-4.1.2/configure --prefix=/usr --libdir=/usr/lib64 --enable-shared --enable-languages=ada,c,c++,fortran,java,objc --enable-threads=posix --enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose --target=x86_64-slamd64-linux --host=x86_64-slamd64-linux
Thread model: posix
gcc version 4.1.2

so im thinking thats the primary issue, i meet all the other requirements. hmn perhaps i should rebuild the kernal...

well, you have gcc 4.1.2, which is the 4.1.x series, not the 4.0.x series. i really think it has to do something with the 64bit modification. because i were able to run it on all my 32 bit slack linux distros (vector and zenwalk), with both gcc 4.2.3 and 4.1.2. 4.0.x was awfuly, yes, i had it on elive (debian based) 1.0 "gem", i could not compile a single program without a bunch of errors.

why don't you get a 32 bit distibution? something "official" with a great repository backing it up?

ya 64 bit processer runing on a 32 bit os,, kinda reminds me of windows,, its a 32 bit gui on a 16 bit os running on a 8 bit processer built with a 4 bit processer by a 2 bit company that cant stand 1 bit of competition. lol ill just go get a hard drive. I guess thats what i get for wanting to use non multi platform software,, on os it is designed for..

or switch to debian 64Bit. if you want to stay with slack, try the 64bit edition of vector linux, it's still in beta thogh, so you will most likely run into similar problems soon.