Ok, so you have the US DVD version of the game? The barcode on the back of your DVD box should read "0 08888 68195 3"? Correct? Ensure that it is, and redownload this file:
http://patches.ubi.com/silent_hunter...vd_1.4b_us.exe
That's the 1.4b patch for the US edition DVD install.
While that's downloading, lets make sure we're starting from scratch.
First, delete any installed version you have so far in the following directory:
C:\program files\ubisoft\silenthunterIII
Delete any other places you've installed Silent Hunter III as well, perhaps the copy I'd mentioned before.
Next, delete the SH3 folder in your My Documents folder and everything below it:
C:\Documents And Settings\YOURUSERNAME\My Documents\SH3
You should be "clean" now. Next install the game normally, with all defaults, from the DVD. DO NOT PATCH YET.
Start the game up and make sure it works, maybe even start a single mission. Make sure it all looks/sounds/acts like you expect.
If it does, by now the patch should be downloaded, so run that patch file. Again, accept all defaults. After it's finished run the game again and test it again as before. If everything is working you should be good to go.
If any of that didn't work, post the exact error messages here please.
Now it's time to install GW. First lets make sure you have a valid install and all the files you need. Find the GW install files and right click on each and check Properties. Check the "Size: 170 MB (178,751,648 bytes)" line and ensure they have the same file sizes as listed here:
TGW11a-1.bin: Icon says 174,563KB - Properties Size: 170 MB (178,751,648 bytes)
TGW11a-2.bin: Icon says 175,098KB - Properties Size: 170 MB (179,300,000 bytes)
TGW11a-3.bin: Icon says 175,098KB - Properties Size: 170 MB (179,300,000 bytes)
TGW11a-4.bin: Icon says 174,956KB - Properties Size: 170 MB (179,154,367 bytes)
TGW11a.exe: Icon says 535KB - Properties Size: 535 KB (547,845 bytes)
If all those files sizes look right, go ahead and run
TGW11a.exe by double clicking on it and accept all defaults.
After it's installed, test the game as before. Hopefully it'll work. Again, if it doesn't post any exact error messages here please.