You could try Streamload.com or mushpot.com

Both give you unlimited storage (while mushpot will during it's beta stage.)

but I mean for the length of time to upload to them your best be may be to just bring an extra Harddrive into the office set it up as a slave and copy the files onto it. I mean 1000 files means about 5GB of music and that will take a LONG time to upload even on broadband. Or you could always burn'em, take ya about 10 CD-R's