I had the same problem when buying my Xbox 360, where you want one, but you don't want to then get one and then a month or two later have them release an even better system.
I got over that fear and just went for it. I asked the same question on here a few months back when I was thinking of getting one, and people assured me that Microsoft weren't thinking of releasing a new system for a long time.
So I went and got one and have never looked back since, it's a great system and I've never had any problems with mine at all.
I'm not a huge gamer though, I just play games on it perhaps once every 2 or 3 days unless I've just bought a brand new game, in which case I'll play on it for as long as I want! I think Xbox 360's can get a little weak if you're one of these gamers who games 24/7. But I don't, and therefore mine has been fine.
My Xbox 360 is a 60gig one, and it plays some of my old original Xbox games which is great! So that's got to be a bonus for you Cape, it was for me.
As for what deals and what games to get on your 360, I havnt a clue what kind of games you like. I would say get the Halo 3 special edition one, but even as bias towards the Halo franchise as I am (I love it to bits), I would say unless you've played Halo and Halo 2, then H3 will be wasted game time, it won't make much sense at all.
But it's a totally awesome game! It really really is!
As is Tomb Raider: Underworld

(I'm pretty bias towards Tomb Raider as well, I like it a lot!)
As for 'online gaming', with the 360, if you want to play
XBOX LIVE, you have to buy a separate package which will set you back a good sum of cash, install it and then play away online. So you don't
HAVE to play online, it's only there if you want to.
I think
XBOX LIVE is great to play on every once in a while, but I don't have a subscription, I just go round to a friend's house who has
XBOX LIVE and we just play there.
I think online gaming is a little overrated, it gets boring fast, for me I find.
But some people like it, because you can download add ons for your games and stuff, like on Halo for example, you can download new maps and stuff for online gaming which they release sometimes. But yet again, I'd say it's slightly overrated. That's just me though.
Anyway, all in all, as someone who has a 360, and just plays games on it every now and then, and watches DVDs etc. I'd say it's a really great system and well worth the money.
Some of the games you can get are amazing, and the enhanced HD graphics are.. outstanding.
Oh, and it's worth mentioning I should think. If you want the very best from your 360, play it on an HD TV. I went and got myself a new HD TV for my bedroom when I bought my 360 and the graphics and gameplay is a lot more smoother and sharper than when I played it on my parent's standard TV downstairs.