Just a quick warning for anyone who really wants to play
Half Life: Alyx. There is no out of the box VR experience because on top of buying the computer, you still need to buy a VR headset system and the hand controllers. Valve has even admitted people will eventually mod in kbm controls, but for now, (1) it's a very expensive add to your PC ticket and (2) PS4 peripherals are not supported if you have those laying around. You can't just run the game for now and try the VR mode later. (If you know this already, cool, but a lot of people seem to think it's like buying RE7)
- Valve Index ($999 USD original MSRP)
- HTC Vive (Pro is veryyyy expensive)
- Occulus Quest ($399 USD)
- Occulus Rift S ($399 USD)
- Samsung Odyssey
So basically, whatever your VR budget is? Add 400 dollars or more, if you can even find one in stock.
Now in terms of what kind of system?
noob-noob Sure, you could use ibuypower, but it depends what kind of settings you want. The GTX 1660 will run VR of course, but not necessarily at a high resolution or frame rate. But if you reduce settings, sure.
Gundam The parts all make sense, but building your own ITX is complicated. Some cases need SFX power supplies, and cooling options are extremely limited. In fact the easiest solution right now is the NZXT H1, which does use an AIO water cooler for the CPU, but the cooler and PSU come pre fitted and installed, making it by far the easiest ITX build you can buy apart from a fully pre-build system (which they also do via their ltsbld service). I have no experience with the SG13 so hard to say if that video card fits (or the RAM?) Usually people who want to know what might fit do a combo of (a) youtube/google searching and (b) comparing specs by looking at the product pdf manuals online.
If you're not buying now, though, RTX 3000 is coming eventually. And end of the year may be Ryzen 4000. The X570 should hold up based on what we know so far, but if its a build for 6+ months from now you should in theory have better options coming.