there are descent mastering software you can buy that will help do a good job, however if its recorded poorly mastering aint gonna help, If I had to give advice on help making your recording top quality from your p.c. i would say invest in your front end i.e. mic pre such as avalon ( my personnel favorite is universal audio Ive compared them head to head with trident, avalon and neve) it depends on what sound you lookin for also your ad/da converters on most computers are cheap, you can buy a mini apogee for under a grand those two or either one you will see drastic differences ( as long as you have a general idea what your doing) ive seen people wit dope equipment have a poor sound and Ive seen others use there equipment they have and have a great sound.