I put this together for a friend in a similar spot as you a little ways back. It's a little under budget, but then again I'm in the USA and don't know EU retailers. This is an idea of what would work well in your position. I'm not saying to get these exact parts by any means, but just as a base to start looking into parts.
You don't need the xeon but seeing as it's a workstation you can't really go wrong. You could swap this out for an i5 K processor and be fine. 16gb will handle anything you are going to be doing. the 750ti is a good card for multiple monitors. The motherboard is a quality board and has plenty of features for a good price.
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Xeon E3-1220 V3 3.1GHz Quad-Core Processor | $191.15 @ Amazon |
| Motherboard | Asus Z87-A ATX LGA1150 Motherboard | $79.99 @ Newegg |
| Memory | Team Dark 16GB (2 x 8GB) DDR3-1600 Memory | $89.99 @ Newegg |
| Storage | Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive | $48.75 @ OutletPC |
| Video Card | EVGA GeForce GTX 750 Ti 2GB Superclocked Video Card | $119.99 @ Newegg |
| Case | Thermaltake VL80001W2Z ATX Mid Tower Case | $22.99 @ Micro Center |
| Power Supply | Corsair CX 430W 80+ Bronze Certified Semi-Modular ATX Power Supply | $29.99 @ Newegg |
| Optical Drive | Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer | $18.89 @ OutletPC |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total (before mail-in rebates) | $676.74 | |
| Mail-in rebates | -$75.00 | |
| Total | $601.74 | |
| Generated by PCPartPicker 2015-06-09 08:17 EDT-0400 |