An average pc will mine at around 4-5kh/s. This is the hash rate. If we had 10,000 pc's hashing at this rate you are looking at potentially 50,000 kh/s.
This would generate around 72 to 90 LTC Coins a Day. The value of 90 coins today is $271 USD. A week would be $1897. A month would be $8131. A year would be $98931.
There is also the potential for LTC Coins to go up in value like Bitcoins have. If LTC went up to half of what BTC coins are now that $98000 could become $1978620.