Haven't seen that Will Smith avatar in awhile, welcome back.
I don't think your recording issue has much to do with the sound card. I don't have an audio background so I might butcher this explanation, but AFAIK 0.0dB is the highest amplitude possible in a digital file without clipping off the top of the wave.
The amplitude (or height) of the waves is measured in negative numbers relative to this point. Music is dynamic Quieter sounds might be -15db, where bass heavy mastered music might be more like -5dB to -2dB on the loudest bass notes. This is why many people use negative dB test tones when setting gains to get the most out of their systems - because they're not going to be listening to 0dB sinewaves, unless they're competing.
That being said you don't need music to hit that 0.0dB mark. For YouTube there are browser add-ons, websites, and software that lets you rip audio-only files (Here's one Firefox add-on I use:
https://addons.mozilla.org/en-US/firefox/addon/youtube-video-and-audio-dow/?src=api). However, you're not going to be getting 320kbps MP3 quality from this, any other software, or any recording setup because
once it's uploaded to YouTube the quality simply isn't there anymore. If you find a site that lets you download 320kbps files like that you're just wasting space. There's probably similar software from other sites. You should be able to use a aux cord to connect your speaker jack to your mic jack to record playback, which is what I assume you're already doing. Go into sound properties by right-clicking the speaker icon in your tray and make sure everything's all the way up for both playback and recording.
Laptop sound cards are largely all the same. If you truly need audiophile sound out of a laptop, get an external USB DAC / headphone amp. I saw a recent thread here that touched on this a bit:
http://www.caraudio.com/forums/home-audio-video/620339-pc-audio-external-amp-dac.html
There are laptops geared for gaming the closer you get towards the $1K mark and continue north. They're bulky to accommodate the required components. If you want to do modern gaming, there's really no substitute, but since you're looking to play older games you can probably make do with a a decent "non-gaming" laptop.
What you'd want to look for is a Dual or Quad-core processor with a high clockrate (3.0Ghz+). A lot of the newer computers boast CPUs with a ****-ton of cores, like (6 or 8), but most of the older games weren't designed to take advantage of multi-core systems, so those extra cores would be a waste. Plus, usually those CPUs have lower clockrates. On software that can utilize these cores, yeah, these things put in work, but on a game that can only use one or two cores - an old Core 2 Duo@ 3.0Ghz would outdo a new 8-core at 2Ghz.
The GPUs on most laptops are soldered to the motherboard as part of the chipset, or are contained on the same chip as the processor (an APU). If you're comparing laptops and you see something like "Mobile Intel HD 5500 Graphics" or " AMD Radeon R5 graphics", If you're looking at modern laptops, the high number the better. (There are discrepancies when you try to compare the latest lines to much older stuff; the number thing doesn't hold true)
Think of RAM like a workbench. The more RAM you have, the bigger the workbench. What you're working on will go on the workbench. If you're working on more stuff than you have room for, you'll have to move some stuff off the workbench (and temporarily into a dedicated space on your HDD or SSD called a swap file, but that's beyond the scope of the analogy). This takes time, but it's manageable. RAM and other types of flash memory got stupid cheap in recent years and PC makers love to dazzle buyers with PCs with lots of RAM. In reality 6-8GB would probably be more than you'd ever need for what you've described, even with audio manipulation and the gaming.
Screen-wise, full HD is 1920 x 1080. Most everyone offers that on any decent sized panel. Obviously since the laptop folds in half the body will match the screen size. What size laptop you get depends on preference. Personally I think 15" is comfortable without being too big.
Bottom line, consider what I've said and look for something in the $400-600 range. Spending more should net you more, but at a certain point it's overkill for what you're doing.
Brands I'd recommend: ASUS, Acer, Lenovo, Sony, and maybe Toshiba.
Brands I'd avoid: HP and Dell
The Chromebook was mentioned, while it's a good machine it's not what you're looking for (it doesn't run Windows). And just putting it out there, if you want to game at all forget the Macbooks - stupid expensive anyway.
