You do know you can install Vista on somewhat newer hardware, right? Or run it in a VM.
If you do want older components you'll have to resort to the used market, meaning that's a *very* local thing.
For the CPU an i7 940 or 965 if you can find one, DDR3 2133+ was a thing but I don't think it was in 2008 so go for 1866 to keep it accurate, 8GB ought to be enough IF you only play games and run software from that era. GTX, I mean... 9800 GTX for the graphics card.
Power supply.... I wouldn't go for an used ancient unit here, use something new, it doesn't has to be modular though, I had a BeQuiet! Pure Power 11 that was 'normal', modular wasn't much of a thing in 2008 so you should go for something like that, 500 watts unless you want SLI or Crossfire cards, older games do have support with the proper drivers, oh man, 3-way SLI with 9800s, those were the days. You'll need more power for that, 750, maybe 800.
Of course the mobo has to support the cards so... X58, but those are expensive, EVGA Classified 4-way SLI was peak X58 but I think it was released in 2009.
SSDs were a thing already BUT you shouldn't go for something old, that and the power supply should be new. You could go for a small 32 or 64 gigs SSD to keep it "real" and then some mechanical drives.
Case I dunno that's up to you. Add a CD/DVD drive with headphone jack if you can find one, you want a TV tuner too so be it, add a sound card as well. You know what was hot in 2008? cold cathodes, yeah, neon lighting, get yourself a kit of that if you want some lighting inside the case.
Thank you very much for your response.
Yes, I am aware that I can install Vista on newer hardware, but I specifically want older components.
Actually, I was considering looking for a 2008 model SSD and power supply, but your suggestion makes more sense. Of course, with the condition of being realistic.
I come across a lot of information regarding processors. It seems that processors like Intel i7 865, 965, Intel Core 2 Quad Q9650, Q9550, Q6600, Intel Xeon X5460, and similar ones were used during that period. There are also mentions of numbers like 771 and 775, but I don't fully understand what they represent. I'm quite ignorant about these topics; I haven't even updated a motherboard's BIOS before.
As for the motherboard, I see names like Asus PQ5 Deluxe, Gigabyte GA-EP45C, and similar ones, but this is the area where I'm most uninformed.
Regarding RAM, as you mentioned, DDR3 or DDR2 with 4+4GB should suffice for Vista.
I will consider your recommendation for the graphics card. I wonder which graphics card today corresponds to the GTX 4090 from 2008? Or what was AMD's flagship graphics card back then?
Actually, what I'm looking for is a PC with the best possible components that a 12-year-old boy, the son of a wealthy father, could convince his father to buy from an average technology store in 2008.
When I was 10 years old in 2008, I used to click on Windows Media Center and try to watch TV, even though I didn't have a TV card in my computer and I didn't even know what a TV card was. It's a curiosity that has stuck with me about TV. Now, I want to build my new system, install a TV card, and watch TV through Vista's Windows Media Center, fulfilling the enthusiasm of the child inside me. It's really strange now that with a single click, I have the ability to watch any movie I want in 4K on Netflix, but I dream of collecting TV cards and DVDs of movies from 2008 and watching them on my new 2008-style computer."