Yeah its really not that big a deal to put a machine together, but it basically comes from having done it lots of times.
If it's your first time, don't sweat about how long it takes you. Careful beats fast every time when you are dealing with hundreds (or thousands) of bucks of components. Once you know the basics, like the mobo screws and what cables from the PSU do what, you'll pick up the pace.
I feel the pain of the guy that fried a mobo during a build. I fried a 6600GT (IIRC) about two weeks after the came out! I was running into problems with something and pulled the card to make sure that the system would still post ok. Problem was, I left the aux power molex connected, and all that voltage but no cooling... Sizzle. Managed to blag that as a manufacturing fault and got my cash back, but still. Ouch.
For a straight build with no OC, as long as you checked compatibility before ordering, then you won't need to read the manuals in depth.
Personally, the thing that takes the longest for me is deciding what to buy, and squeezing every last cent of value out of the budget that I have. Often takes me weeks or more to find the right combination of gfx, chip and RAM that will fly for me, but thats part of the fun of course

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Take it easy and you'll get there. Will be MUCH easier next time. Everything can only fit in one place after all
