legacy question

i have doom legacy v1.30 for dos, i use dos because windows is slow on this PC. i have to ask is 320 300 the only res i can play in on the dos version, when i downloaded the dos version it said high res. also i have dos, not winME, and i have no sounds i belive, %95, that this is because of my soundcard IRQ's. the card works in windows but not in dos. it is set up correct but i dont think any dos programs use a irq above seven, i can set it at the lowest 9. any help on info would be welcome