Is it permissible to purchase a computer and media equipment by installments with an excess (interest) from a usurious bank, and what is the ruling on the bank's supplier of the goods?

It is forbidden to deal with usurious banks because they engage in forbidden usury, which incurs the curse upon its consumer, its provider, its scribe, and its two witnesses. It is also forbidden to supply the bank with goods that it uses in forbidden contracts, because that constitutes aiding in sin, which Allah has prohibited.