Quite a wealth of recordings available of Chicago Symphony Orchestra playing Mahler 7:
The one bloke mentions led by Solti, Decca analog original (24-bit remastered on the "Originals" reissue) from 1971 recorded at University of Illinois Krannert Center;
James Levine's 1980 Mahler 7 recording at Medinah Temple, with 24-bit remastering, included in Levine's Mahler "cycle" (minus 2 & 8, but with a full reading of Cooke edition 10th) made with Chicago (3, 4, 7), Philadelphia (5, 9, 10) and London Symphony Orchestras (1 and 6, possibly Fletcher in 1978?).
The Levine set is bargain priced 10 CDs (no liner notes). His Chicago Mahler 3 sounds
splendid in the remastered set, but is
mislabeled on the set box and CD sleeve as being "Philadelphia Orchestra" recorded at Medinah Temple (Adolph Herseth is credited for posthorn solo);
Claudio Abbado in 1984, recorded with fine digital Deutsche Grammophon sound at Orchestra Hall;
and lastly (?), Pierre Boulez October 2010 live Orchestra Hall performance(s) available for online listening until December 14 at the CSO website:
http://cso.org/ListenAndWatch/Details.aspx?id=13716" target="_blank" target="_blank" target="_blank
As an inexpensive "package deal", Levine's set includes several highly regarded performances, and sounds great in 24-bit remastered sound (better than an earlier RCA/Soundstream release I own of Mahler 7 on CD). Both Levine and Abbado take just over a minute longer than Solti in the final movement. Solti's reading is indeed impressive, if slightly "frenetic" at times for my tastes. Solti's 1971 recorded sound, even with remastering, isn't quite up to Levine's or Abbado's, IMHO.