windows installer/net framework problems

Compaq Presario ms w ME v 4.90.3000 5WV280
128 mb of ram 900 mhz Amd Athlon processor
30gb hd with 23 gb free
IE 6 SP1 plus internet tools
F sys 32 bit

when i use Belarc advisor it says that i have windows installer msiexe.exe
modified in 2002 (i just picked up this pc in aug 2009)

it also says i need to reinstall UPDQ823559.which i tried and it does not
seem be there.

when i go to download most programs,( examples- RaydarSync, or filehippo
updater, or openwith.org etc etc.) they first say that i need netframework
two, the program then asks to download it and it cannot because it says that
i need the prerequisite ms wiindow install 2.0 (Instmsi.exe). i also get the
message that i am missing DLL file MSCOREE.DLL.

i have been to ms download sites for the installer, the update and the net
frame work a zillion times, they are not lisred in add/remove and i do not
know how to find them or open them if they are in my system somewhere.
i am frustrated and need help straightening all of this out. i do not know
if i should try AAron Stebner's net framework set up verification tools etc
and or the windows installer clean up utility or both or not ??????????????

please help !!!!!