1. Concerning system requirements, Valve states the following:
- Windows 98, ME, 2000 or XP
- 64 MB RAM
- 400 Mhz processor
- 1GB HD space (recommended)
- Broadband Internet connection (recommended but not required)
Strangely enough, they didn't even mention a gfx card, but of course it depends on the settings... if you want to play it @ 1280*960 with all eye candy activated, you will need a better gfx card. But if you switch the screen resolution to 800*600, your Voodoo 3 should be fine. I used to run Counter-Strike on a PII-266 with 12 MB Voodoo 2 @ 800*600 and 96 MB RAM, and it was quite ok.
It also depends on the maps (levels) you want to play. If you stick to the standard ones, everything should work fine. However, if you play custom maps designed by hobby mappers, you may experience lags if the map is graphically VERY demanding.
The same goes for player and weapon models: It is possible to replace them with inofficial custom models that look a lot better than the defaults. However, on a slower PC I would recommend sticking to the default models, because they are less demanding.
2. Steam vs. Non-Steam
STEAM is actually a kind of loader program for Counter-Strike and other Half-Life mods like Day of Defeat. It is also used by Valve to enable users to purchase, download and play upcoming games designed by Valve. STEAM will maintain a connection to Valve's servers and provide the following functions:
- It will automatically check for updates to the STEAM client itself and all installed games.
- It provides a server browser to find game servers on the internet, connect to them and keep them in a favourites list if you wish.
- It has a built-in kind of instant messenger. After adding your friends to a list, each time you open the "friends" window in STEAM, you will see who of your friends is currently online and chat with them. If any of your friends is currently in a game, you can quickly join him without having to look for the server yourself first.
So much for the theoretically nice part...
However, Steam also has some disadvantages.
- It can be quite a b*tch, and it absolutely depends on Valve's servers. If the servers are down or if there is some Steam error, you won't be able to play any of the games that you installed via Steam.
- When there is an update, all Steam clients around the world will automatically try to download it as soon as the user starts a game. This frequently causes the servers to be overloaded soon after the release of a new update or patch.
- Whenever a new Steam version turns out to be flawed, you won't be able to play. This happened several times already, and all you can do is wait until a new patch fixes the problem again.
- Many people experience lock-ups, crashes and other inconveniences with Steam. Most of the time, it can be fixed, though. I wasn't that lucky, but that's just my personal experience...
The problem is that the only official CS 1.6 IS Steam CS 1.6. All so-called non-steam CS versions are versions that have somehow been cracked or modified so that they don't need Steam to run. Most of these versions have been cracked or ripped by people who wery pissed of by Steam... 9_9 The non-Steam versions cannot connect to any regular Steam server and must rely on their own servers, which are scarce at the moment.
The most important point about these versions, however, is that they are unofficial, and it can be doubted if they are legal at all.
(If anybody feels tempted to start a discussion about this topic, just tell your teddy bear everything you think. It will listen to you - I won't.)
Phew, I hope this blurb was a bit helpful!

Amazing that there are still ppl who are totally new to CS. But of course, with
that PC, you won't be able to play most of the more modern ego shooters. 9_9