vB 4.1.4 - Vulnerable to SQL Injection?

[thetechgenius]

So I have a few enemies online, and a few competitors.

One of them said they are going to hack my site using an SQL Injection Exploit. However, I think they are full of it. But just to be on the safe side, I thought I would post here to see what I can do to make sure it doesn't happen.

• How would I find out if my vB 4.1.4 is vulnerable to SQL Injection?
• If so, How would I fix that vulnerability if it is vulnerable?
  
• Or maybe vB has nothing to do with SQL Injection?
• Does it have to do with only my MySQL Server and/or PhpMyAdmin?

I also have an legit SSL Certificate, and have my site running on HTTPS throughout the entire site. I also have a legit wildcard subdomain SSL Certificate running on my PhpMyAdmin sub-domain, so my PhpMyAdmin sessions will be secure through an SSL Connection.

Note: I have my vB 4.1.4 running on my own Dedicated Server.

OS: Windows Server 2008 R2
CPU: Intel Xeon Quad Core CPU
RAM: 12GB ECC RAM
ISP: 90Mbps Download | 90Mbps Upload - Dedicated IP
NIC: 1 Gbps
Webserver: IIS 7.0 (Maybe 7.5, not really sure)
MySQL: Version 5.6
PhpMyAdmin: Version 4.1.9

If you need any more info, just ask. And thank you.