How much would my PC be worth in 3 years?

Its PB ixtreme with 1035T, 6 GB RAM, 5570 (which I will be upgrading to either 6950 or for the 7950 or nvidia equivalent), 1,5 TB HDD, multi-in-one card reader and DVD-super multi drive. I bought it for 999€ (overpriced, but I needed new pc asap). I'd hope it would cost some 400€. Too optimistic or...?