First of all, get good anti-virus and other scanning software. Run them regularly and keep them updated! This doesn't matter how much RAM you have. Make sure the stuff that is installed and running on your computer is the stuff that should be installed.
I recommend free software (and if you look around, you will see many people and sites, including Google, that agree with me).
The
Google-Pack includes
Ad-Aware SE Personal. Lavasoft no longer distributes this on their own; they just sell the pro versions on their site. You can download just this without the rest of the pack.
The Google-Pack also includes
Norton AntiVirus. I recommend you do
not get this.
Avast anti-virus software is free and just as good (if not better). You will have to register every year or so with a valid email address, but they are a trustworthy company, so this is safe. If you are paranoid, just create a disposable Yahoo email account or something.
Now, as far as RAM goes, yes - 256 is the bare minimum for running XP and maybe one instance of Notepad. :original: You really need to at least double that. There are many tips (probably in these forums) related to turning off other apps, lowering graphics details, and so on. Maybe if you use all these tips and turn the graphics down to the very minimum, you can get by with 256. But if that is the case, you might want to download some old-fashioned text adventures instead of playing MM2. :original:
So save up for some RAM just like you would save for the next ZT expansion. In fact, it is
better than an expansion, since it is something that will impact
everything you do on your computer.
p.s. The first computer viruses pre-date the Internet. Just because your computer is not connected to the net does not mean it is clean. I've read studies where someone "dropped" an infected (but harmless) thumb drive outside an office, and then tracked how quickly it spread in the office network (which was not on the net.)
Of course, if your computer is not on the net, this makes it a bit harder to install the software I recommened above. But you should be able to transfer it on a CDRW, thumb (USB) drive, etc.