Linspire setting up the default user as root is very bad. So setup a regular user for your dad to make things safer. As root you can have a program barf that will ruin system files, if your just a regular user then it limits the damage that can happen.
This is my main problem with linspire.
Linspire package management is a bit annoying, you have to pay a monthly fee to download programs. Almost everything is open source and is aviable for Free in other channels, linspire just renames a bunch of it and that's what you install thru their pay service.
there are a few genuniunely useful stuff of Linspire that you get that you don't get thru other distros.
for instance Linspire pays licensing fees to get support for Microsoft window media codecs. They also have deals for some programs like 'Cedega' (normally 5 bucks a month subscription fee, linspire charges a price that may or may not be worth it depending on how they do updates), or some commercial linux games that are fun (like marble blast gold, which is fun for adults and good for young children.. or quake2 or whatever). They have AOL dialers, and other things that normal Linux distros don't have.
Stuff like that. So it may be usefull service to have and it's not tooo much, like 60 bucks for the expensive version.
Linspire itself is Debian based. If you try linspire out and it doesn't work out for you then Ubuntu or Debian can easily replace it on any computer sold with linspire.
The modem may be tricky though.. Linspire may go into deals to get special support for it.
Keep in mind that with these dirt-cheap systems that they aren't going to be very high quality. They'll probably be fairly noisy and you have to have a safe place for the computer box since they are probably flimsy. I've been told by a person that in order to get their computer to work properly that they had to reinforce the mounting of PCI cards by using those stripper-style packaging tie downs.
But after that it works, so a crappy computer that works fine and a expensive computer that works fine are both the same things: computers that work fine. 200 bucks is a nice price after all.
Also you'd want to upgrade your machine's memory to 512megs of RAM if you can. The CPU is plenty powerfull enough.
Also find out if it has a AGP port or not because you may want to upgrade the video card later if you can. (buy a ATI 9200 or _older_ card or get a newish Nvidia card for good Linux support (good 2d support, if you want 3d then it requires propriatory nvidia drivers which you should inquire to Linspire about) if your curious).
Some of these machines will only have PCI slots and PCI video cards can be hard to find and can be expensive compared to AGP or PCI express ones.