Then you're going to have to build your own, go to Newegg.com, they sell plenty of parts there for reasonable prices(4 GB of Ram for under 200 Dollars FTW!) and also, look up some tuts on building a PC, don't buy everything at once, plan it out and then buy at certain times, then once you have all pieces together, begin putting it together.
DONT, I REPEAT, DON'T FORCE THE PIECES INTO THE MOTHERBOARD, TAKE YOUR TIME! dont be in a rush either, take your time.
And remember to wear rubber gloves, or if you can't touch the case of the computer every so often, and before you begin installing anything. Computer parts can be easily ruined by static discharge. I learned that the hard way
I would get a new CPU, if you get an old one, you wont be able to upgrade it, all CPU's now are coming out as quad core, duel core is a thing of the past, no more will really be made, so buying a old CPU is like buying a old PC.
The only way you can upgrade a old cpu to a new one would be to use a new motherboard, not all motherboards fit the same sized cpu's, then again, your hard drive will need to be reformatted as most hard drives will not run on a different motherboard unless it's the same model.
You need atleast 250 now to buy a cheap PC. I saw one at office depot this week
amd athlon 64 4000+
good specs for a good price of $250.
But a PC that cost 400-500 will be 10x better.
OR, with the 140 dollars you have right now, go get a OLPC, those small green laptops, buy one, and get one for free! (the free one is sent to poor kids in a third world country for education purposes)
140 dollars will not get a mac laptop, mac's average around 1000 dollars or more for a laptop, a windows based machine for 500-600 dollars could easily compete with a Mac and has been proven many times.
* 2.0GHz Intel Core 2 Duo
* 1GB memory
* 80GB hard drive1
* Combo drive
Thats the most basic macbook there is and it cost over 1k. (direct quote from apple.com)
Heres a windows machine that runs for half.
15.4"-diagonal widescreen WXGA (1280 x 800) BrightView LCD screen
AMD Athlon 64 X2 Dual-Core Mobile Technology TK-57 operating at 1.90GHz
1.0GB of DDR2 SDRAM memory (2 x 512MB)
120GB 5400-rpm Serial ATA (SATA) hard drive
SuperMulti DVD drive with Double Layer support
5-in-1 memory card reader
$599.99 (direct instore office depot pricing)
Though the CPU may not be as good, I'm sure for a CPU just as good or better than the macbook's it doesnt need to double the cost of the machine.
Alienware is a piece of junk now adays, when they were their own PC company, they were still expensive, but you got a quality product, now Dell owns them, their poor customer support and poor build quality and care is what we know as alienware. If you want a PC for 3000 dollars, go get a voodoo, HP owns them, and HP is known for their quality.
Though a 3000 dollar PC is crazy, I would look for something in the 400-700 dollar range for internet use, burning dvd's, and playing some games. They wont run games at full graphics if the game is brand new, but they will probably run with lower graphics. Anything else such as surfing the net, and running programs, a cheap PC can handle easily.