pentium D 2.66 GHZ CPU and an old ATI GPU
You should mention what kind of GPU you have.
Probably, CPU 2.66 GHZ give you nothing except headache. Too slow for current litecoin difficulty. I'm talking that because my i5 3.70 GHz 4 cores, give me nothing, it is really, really slow, e.g. I try to mine on
http://coinotron.com with litecoin. Full speed. About 2-3 weeks ago. 1 day give me ~ 0,00001 litecoins. Game completely over.
You need to get calculator.
http://btcsec.com/calculator/http://tpbitcalc.appspot.com/Use better google for alt-coins calculation, for litecoin too.
Get you speed from here:
https://en.bitcoin.it/wiki/Mining_hardware_comparisonYour diagnose is
Only pool:
https://litecoin.info/Mining_Pool_Comparisonhttps://en.bitcoin.it/wiki/Comparison_of_mining_poolsYou better chose alt-coin by it's difficulties, if you can get anything, you should get. Otherwise, just don't touch it.
Super earlier alt-coin may be available, plus, look at specific alt-coins, not a scrypt.
You can't mine sha256 alt-coins anyway. Scrypt - too very high. Look at:
Quark (QRK) blake, bmw, groestl, jh, keccak, skein
https://bitcointalk.org/index.php?topic=260031.0Blakecoin (BLC) blake-256
https://bitcointalk.org/index.php?topic=306894.0https://cryptocointalk.com/topic/1235-kimcoin-kmc-information/https://cryptocointalk.com/topic/1196-cthulhu-off-information/https://cryptocointalk.com/topic/1055-kingcoin-king-information/Datacoin (Prime - clone)
https://bitcointalk.org/index.php?topic=325735.0etc.
You have real chance with alt-coin that have no enough miners ( difficulties ), with very specific algo.