It has been about six months since we last looked at K320 models, and it has only gotten stranger. You can still happily buy K320 1BU's (the i5) machine at Amazon. That's what I bought and I'm very happy with it. OTOH, the Lenovo website cheerfully sells only 1DU's and 1FU's (i3 and i7). To review in short:
1AU & 1DU - i3 with integrated graphics
1BU & 1EU - i5 with GF310
1CU & 1FU - i7 with HD4650/GF320
That's a bit of a simplification, for more detailed specs see:
http://www.lenovo.com/psref/pdf/icbook.pdf
Now if you were paying attention earlier, you may remember that the A/B/C models were released to outside vendors, including Amazon, although we never saw a 1CU in stock anywhere. The D/E/F models are sold only on the Lenovo webpage, although they tend to come in and out of stock and with different shipping dates.
And of course, there is also the K305 series, with AMD chips. but it always says "shipping in more than four weeks". Can't imagine why Lenovo offers both chip options, but you never know.
Now hang on, because here comes the K320 1LU and 1MU!
These mysterious desktops are not referenced anywhere in the Lenovo website or on their official product line PDF (see above), but they are starting to appear on various reseller pages, including Amazon. In a reversal of the normal order, the 1LU is the i7 model, and the 1MU is the the i5 version. The 1LU is referenced as "coming soon" by Amazon, but a company called newegg.com claims to have them in stock and even has a short buyer review of the product!
Is there a new i3 model as well? Google finds no 3019-1KU or 1NU, so I guess not. But hang on, because in the wild world of Lenovo marketing, anything is possible.
In the meantime, many resellers still have plenty of 1BU models. It is better equipped and slightly cheaper than the 1EU on the Lenovo page. Details on the K320 review topic in a related topic. I keep hoping someone from Lenovo will read this and clear up the model muddle. Good solid machines, very strange marketing!