Taking everything in consideration of the stuff you are going to host, i can say now that VPS is going to run out of memory really quickly.
Try to bump that memory to 1gb or 2gb.
- Apache 2 (Needs to optimized)
- Nginx (Lightweight and easy on VPS)
- Lighttpd (Lightweight webserver)
- Php 5
I would go with Nginx.
- Amavisd-new (Spam and antivirus interface for MTA)
For mail, i would consider Google Apps. One less service to host and manage.
- Iptables (Firewall)
If you want to you can install ISPconfig 3 to have a nice interface for your services but if you only gonna host one domain than ISPConfig3 is maybe overkill.