To me "future proof" must also involve the ability to upgrade certain key items in the future. Namely the processor and the graphics card. If the computer didn't have a PCI Express slot I wouldn't consider it and if there was no info on the motherboard so I could find if it would take a faster processor I also wouldn't consider it but I couldn't afford a dual core processor so had to look for a board that would take a dual core in future. I build my own PCs and am quite willing to add or replace anything on my PC which is somewhat different to the majority of users.
The Carrera and the Time you give a link to are very fast machines and will likely do you for some time to come. Due to them both having high speed dual core processors the need to upgrade the processors is secondary. More important perhaps is the graphics, the Carrera mentions having a 16x PCI Express port so it should be ok but the Time one really does not give me enough info to base a decision, the Carrera is based on a lower end ECS motherboard but the Time one gives no info at all.
Personally I would have a look at the PCA charts in the latest magazine and start there.