Well, apologies, but I'm going to widen rather than narrow your choices.
Those AT mics in the link are cardioid--directional. They need to be pointed directly at what you are recording. It depends how you are going to mount them--you don't want them moving around during the recording because they will get louder and softer. Don't know how you were using the internal mics, but cardioids do best in a fixed place.
I see they have an XLR-to-stereo cable connector.
People who have those ATs do love them, and they are a bargain.
The Core Sound mics are omni--they record all around, so they are more forgiving about placement and less susceptible to wind noise. Core Sounds require their own battery box, with a special connector, so it's all-or-nothing Core Sound if you do that. You do not need bass roll-off--you can roll off bass if necessary after recording.
A widely recommended alternative here is Church Audio mics, which are excellent quality, handmade by Chris Church, and somewhat cheaper than the Core Sound package--if you're patient.
I have a pair of CA-14 omnis that sound wonderful and are optimized for loud music recording--a little less sensitive than other mics I've owned, which is good. They're larger than the Core Sound--thumb-tip sized instead of pencil-eraser size--because their windscreens are built on.
Since I got those he came up with another omni, the CA-11 MK II, which are also supposed to be pretty swell.
Church mics are typically terminated to a regular stereo miniplug, so they could go into your Mic-in input directly for quieter sounds, or they can be used with his sturdy little UBB (Ugly Battery Box) into Line-in for louder stuff. I use them with a Soundprofessionals battery box because I needed one in a hurry.
http://www.soundprofessionals.com/cgi-bin/gold/item/SP-SPSB-10Church Audio's website is kind of sketchy at the moment
http://www.church-audio.comThough if you click around you'll see he's more affordable: he is offering two CA-14 pairs (omni and cardioid) and a preamp (which is more versatile than a battery box, though I find it overkill for typical live recording) for $299. A mic and battery box combo should be considerably less than $300.
If you look at the Retail section under Marketplace you can find the Church Audio listing (out of date now, unfortunately--people snapped up his wild half-price Xmas sale). You can send him a direct PM about an order.
He builds them himself, and they can take a month or so to arrive from Canada. But if you pair the CA-14 omni (or the CA-11 perhaps) with his UBB--Ugly Battery Box--you'll get some fine recordings.
One more place to look if you need the mics fast is Sound Professionals.
http://www.soundprofessionals.com/cgi-bin/gold/category/110/micsDon't get the BMC-12, which have incorrect specs--they are speech mics, not music mics. (I've complained about that to SoundPro but they've ignored it.) If you want a starter pair, the BMC-2 are pretty good, but the Church Audios are a serious step up.
Ok, and one more: Naiant X-X.
http://www.naiant.com/xxspecification.html I haven't used these but Naiant is serious audio geek stuff and I'd expect them to be good. Note that the mics are the tinier end of the picture--I think the fat ends are XLR connectors. You'd get a stereo pair with a miniplug, $69, and probably get a battery box from SoundPros. Jon Stoppable from Naiant is also on taperssection for questions.