Okay, sorry about my mistake. Since I've already decided that the x800 is too expensive for my tastes, I haven't studdied much about how long it takes to get one. Perhaps you might've had better luck buying one on EBay, but oh well...
$4,000C? That's what, about $3,300US? That's still quite a bit. But looking at those, your computer looks in a condition eerily similar to mine, with an Athlon 64, plenty of RAM, and a badly out-dated video card. (but I'm stuck with a Radeon 7000, which is worse, having no pixel shader capabilities...)
However, if you have the money to spend on just about any new video card, try searching EBay for one. Just be careful to make sure it's a legitimate sale; make sure you examine to see that the seller is good, and all that online auction advice crap. an X800XT PE will probably be abit more expensive on there, though, but it's your best bet if you still want that card, and want to recieve it before it's outdated. Otherwise, the X800 Pro and 6800GT aren't anywhere near as over-demanded, and are cheaper to boot.
If that's not the case, $180(canadian) would be enough for a 9600XT. It's highly underrated, getting plenty of good performance. If you play without Anti-aliasing, it will play games for the next 2 or so years with maxed settings, getting 60fps, I bet, particuarly with the rest of the machinery you've got.
Let's see... What's that minimum specs for Half-Life? If I recall correctly, it's a Pentium 200MHz, 32MB RAM, and no video acceleration required. Believe me, that won't play Half-Life 2, and I don't have to try it to find out. However, if you were trying to get at the fact that brand-new games like this are quite playable without having to steal technology from 4 years into the future, you are correct. Even when Doom3 hit the shelves, you could use a Radeon 9800XT, max the settings, and still get 60fps. I imagine that those of us who've got an Athlon 64 to do our bidding are quite in the clear, as soon as we do something about these horribly outdated video cards...
Wake up, George Lucas... The Matrix has you...