Justin218:
If you're interested in HL Blue Shift for the solo play, do yourself a favor and get this:
Half-Life Generation Pack
for around $35 shipped Fed-Ex 2 Day. CompuExpert is a very reliable company.
You'll get: Half-Life "Game of the Year" Edition, Team Fortress Classic, Opposing Force, and Counter-Strike in one package. As far as I know, you need Half-Life for any mods.
Blue Shift does include the Op-For expansion, but it also has a $10 rebate if you already own Op-For. It also has code for high-definition charactor and weapons models, which will automatically update the whole HL series on your system.
The biggest complaints about Op-For and Blue Shift is that they're "too short". If you play your cards right, you can have a solid month or more of HL-series solo play alone for under $50 - then you can spend the rest of this year trying to recover from your online addiction to HL death-match, TFC, Op-For CTF, and CS.
Heh - I "upgraded" to cable just for CS . . .