Hi She-Wolf. If you have the means, purchase the SH4 Gold edition. This DVD is all you need. It contains the 1.5 addon, without the need for a seperate D/L and activation codes.
The latest TMO, as well as most of the mods are geared for 1.5. There may be some mods that are still available for 1.4, but I don't think they're still supported anymore.
If your system has 2gigs of RAM or more, than you could try the 4gig patch. It's really not a patch, but a small utility that allows programs (not just SH4) to use more than 2gigs of memory. This has solved alot of unknown CTD's for alot of folks, including myself. I use it for all my sims. It's easy to set up, and it works wonders. The only thing I'm not sure of off hand, is the OS requirements. It's easy enough to search the forums and find out though
