I'd rather they didn't push, and actually release a complete game.

So what if Doom 3 comes out a couple months before? People are gonna buy either / both games no matter what. This way, they have a chance to get over Doom 3 before starting on HL2.

It's actually better this way, rather than a close release, or HL2 coming out first. Due to the small MP portion of Doom 3, there's not as much longevity in it (mods aside). HL2 will probably amass a huge online following again. This way, both games get a fair share of the target audience without any major competition