Looks good to me. Right now I'm also using my laptop which isn't the highest of specs.
My desktop computer is sitting dissembled in a corner since I believe either the CPU or motherboard went bad. I have a few parts I want to sell to get it back up again but it is not a priority for me at the moment. Here is what I have laying around:
CPU: Core i5 2500k
Motherboard: Asus P8Z68 V-LE
CPU cooler: Hyper 212+, Noctua NH-D15
Graphics card: Asus Direct CU II HD 7950, EVGA 9800GTX+
PSU: Enermax Naxn 550W, XFX PRO 550W
HDD: Seagate Barracuda ES 750GB
RAM: G.Skill Ares 2133Mhz 8GB
For headphones I have a pair of Koss KSC 75s and Yamaha EPH-100 for portable use, DT 770 PROs, Sennnheiser HD 518s, and Panasonic RP HTF 600s for home. Although I do like to take the Beyers with me on the go. I have an M-Audio Fast Track as an audio interface which I use as a DAC/AMP. On the go I use them unamped with my phone, however I have found it barely scapes by. I'm thinking of building a CmoyBB portable headphone amp.
I have owned the m50 before as well. My 518s sound very similar to the 558/598. Out of all three the Beyers can do what you're asking for the best.