Obivouisly you need sound lol.But i hear yah when it comes to spending money on something yah don't need.But i personally love the sounds from gaming , and also i play alot of music on my comp , so sound is very important.Sounds really depend on what games you play and what speakers you got for your system.
For example if you play Starcraft and have a standard pc speakers, then i would get a Soundblaster PCI 128 or a card like that.Now if you play Doom 3 with 5.1/7.1 sound system bone out the cash for a Soundblaster Audigy Pro Platinuim or a card equal to that.
So as you see , it's really up to you and your needs.It's like a gramma buying a porshe 911 gt3 to go grocery shopping

Go for what you think you need not what a sales person saz.
Good luck and cheers
Backyardtechie