The first computer the man bought represents him from birth. That which makes us unique consciousness (spirit) is symbolized by the man's personal files such as Word documents, which the man accumulates with time. That which we use to express our uniqueness is symbolized by the software programs to use those personal files such as Microsoft Word (soul), and the various other hardware items, such as hard-drive, RAM, and processor symbolizes our (body). Our spirit, soul, and body work in tandem to express our uniqueness. With time, symbolized by after a few years, the unprotected computer gets clogged with viruses, trojans, spam, and advertising pop-ups, representing how we start off life naive and do not fully protect ourselves in life and get clogged down with sin and negative experiences in life, which eventually make us break down (ie die), symbolized by the computer getting old and slow, requiring it to be replaced (resurrection to spiritual life).
The man wanting a new computer represents our desire to have a new soul, spirit, and body in the resurrection that is not tainted with sin. The expert represents Jesus Christ, who saves the man's spirit (personal unique files) and cleans it, and transfers this unique spirit into a new body, with new soul and now clean spirit. Our new bodies will have upgraded hardware, which represents our new spiritual bodies in the resurrection that will have supernatural abilities like the angels. The protection programs (firewall, anti-virus) in the new computer represent how we will have learned from the human experience how to protect ourselves from sin, so we never have to die again (ie replace the computer). Our new uniqueness will be fully expressed without sin, as our new spirits, souls, and bodies glorify God for all eternity.
A little more on the body, soul, and spirit. Our body is easy to understand, since we're so fleshly made. The mind is the soul. Some Bible verses talk about animals having souls (Psalm 74:19). The soul then is connected to the animal brain part of us, rudimentary instincts, feelings, primitive consciousness, as even dogs have discernibly different personalities. Animals have this basic emotional makeup, like humans, and instincts and primitive/basic consciousness, and some dogs have demonstrated heroic capabilities, dying sometimes in certain situations to protect/save their owners. As they say, "a dog is man's best friend." But dogs don't think the same as humans, don't talk, don't contemplate death the same way, think about God, afterlife, etc.... THEY HAVE NO SPIRIT! They only have souls. King Nebuchadnezzar in the Bible lost his spirit. God took it away in punishment, and he ate grass like an animal for 7 years (Daniel 4). He acted like a soulish animal for many years. Then God gave him his spirit back and he could think like a man again, with memory of his crazy years. Even praised God for coming to deeper understanding of God's strange ways, as I understand too.
The human soul is capable of these animal basic abilities and has both positive and negative emotions. The spirit in man has higher consciousness and can think and be self-aware in ways animals can't, and is only capable of positive emotions. Being human, that is hard to understand that the next life is only positive emotions because we all have negative emotions sometimes too. "And it shall come to pass, that as the LORD rejoiced over you to do you good, and to multiply you; so the LORD will rejoice over you to destroy you, and to bring you to nought; and ye shall be plucked from off the land whither thou goest to possess it." (Deuteronomy 28:63) The carnal mind (soul) will read this and think it means the Lord literally rejoices to destroy people, as if He enjoys causing suffering and destruction in people's lives. The spirit mind (animated by Holy Spirit) understands this simply means the Lord AND HIS ELECT, in the next life, experience only positive emotions always, something to look forward to in the next life.
So Romans 12 talks about renewing one's mind, which I have, and this is why I understand these things and can explain it. Those who have not renewed their minds will probably disagree with all I have said, and think mind is somehow different from the soul and/or the spirit has negative emotions, because it is often difficult to discern the difference as human.