One of the nice things about the c1000's is that you can use them without phantom power- they can run on a 9v battery.
If you don't have phantom power, those 2 mics for $200 bucks is a *really* cheap way to get into condensor mics. I've got a couple c1000's and I like them for acoustic guitar. I've used them for vocals and they worked OK for me, but I have "better" mics that I use now. I even used it for electric guitar and it sounded OK to me, but I tend to use a 57 for that most of the time.
The c1000s was a step up for me when I bought it (before all the cheap mics started coming out) but they aren't really the best deal around these days.
The 603's that I have sound very nice on acoustic guitar, but they don't handle vocals as well as the c1000's. The 603's do electric, clean and distorted, about the same as the c1000's to my ears. I've read here that the AKG's have a harsh high end, but you're talking to the wrong guy to verify that.
Here a couple of songs I've done with those mics-
The c1000's are the only mics I used on the guitars for this song:
Mute (3.7 Meg)
The guitars on this one are mainly the 603's with a low freq. undercurrent of Studio Projects C1's. Not exactly a fair comparison, but it might give you a chance to compare the high end.
The Mouse and The Eagle (3.4 Meg)
You can find low-fi streaming options at chrisshaeffer.iuma.com, if you like.
In short, I'd recommend the c1000's only if you have no phantom power. If that's the case, then don't feel like you are getting a raw deal- they are good mics at that price and pretty versatile. If you do have phantom power there are less expensive options availible that might serve you better depending on if you need a stereo pair or a good quality vocal mic.
And not to counter Tdukex's good advice, but I would stay away from the ECM8000's unless you know a bit about what you are doing. Those omni mics can sound great but are quite a challenge for many home recordists. They aren't forgiving.
Take care,
Chris