Old Mac Pro or newly built Hackintosh?

I want to build a dual boot Hackintosh (Sierra and W10), and I have 2 choices. A friend of mine's mother just quit her job. She's selling his mid-2009 Mac Pro for 300€ but I think she'd let me take it for a little less. I took a look at it the other day and i was a little bit disappointed (to be fair I had high expectations (I mean we're talking about a thousand-euro powerhouse): - Single CPU version, an Intel Xeon W3520 4-core @2,6GHz - 6 Gigs (3 x 2) RAM, DDR3 @ 1066 MHz - Radeon HD 4870 - two 1TB HDD, WD black caviar. Bus speed is SATA 2 - Apple's optical superdrive - Really dirty

I already read online that you can boot a newer firmware on it (version 5,1), letting me run Sierra and installing faster RAM, so that's good There would be some obligatory shopping, like: - thermal paste, to put on the CPU after cleaning all up - a wi-fi card or the expansion wi-fi/BT - Usb 3.0 Card - an SSD for the OSs and a PCI/SATA 3 card to mount it And maybe - More ram - Newer GPU (but that's not a big deal, more on that later)

On the other hand, here's a build i sketched. I wolud proceed to install both OSs on this machine, too, though it's going to be a bit more tricky

PCPartPicker part list / Price breakdown by merchant

[would buy used RAM in either case; prices are from italian sites]

I have to mention that I don't want to build the ultimate workstation, nor want to game on it. It's main goal is (beginner's) music production and to be an all-in-all good desktop which will run mainly W10 but switch to Sierra when I want to.

All this being said, what would you suggest me? Can the old Mac still be considered good for my use? Or my build, even if it's slighlty more expensive, it's gonna overpower the 18 kgs monolith?

Also be kind, it's my second ever attepmt at a build haha. And ignore the possible bad english Thank you