Anti Virus/Maintanance Software & Upgrading Hardware

Just a few more questions before I place my order (finally) this month for the Mini.

Do I need any software such as Anti Virus, System Works, Firewall, etc. with Mac?

Future Upgrades. How easy is it to find/swap Hardware (Dual-Layer DVD, possibly HD-DVD/Blu-Ray and Hard Drive) for Mac?

Thanks.

no antivirus or all that other stuff is needed, maintenance is fairly simple, and there are free apps that work great, os x has a built in firewall. its fairly easy to switch hardware in a mac.

With a Power Mac tower, swapping hardware is easy--the case pops open as easily as the best PC cases.

iMacs, eMacs, and Minis are a little tougher to deal with. For one, they have slot-load optical drives; for two, they're packed pretty tight. Getting to a Mini or iMac's hard drive is possible, but if you want to add a dual-layer DVD drive, you'd be better off with an external FireWire drive.

Is this what you're looking for: http://www.mcetech.com/minidvdr8dl.html? As far as security software goes, Symantec announced some time ago that it was no longer developing/upgrading its Mac software except for Norton's Anti-virus. If you feel the need for such software check the test reports on sites like Macworld or MacAddict. They often run comparative tests.