With classical cryptographic algorithms under threat from the development of quantum computing, the transition to quantum-resistant replacements is critical to network security worldwide. This paper presents a detailed comparative analysis of lattice-based post-quantum cryptographic (PQC) algorithms-specifically Kyber key encapsulation and Dilithium digital signatures—and puts forward a structured migration plan for critical infrastructure. We evaluate these NIST-selected algorithms at different security levels (128, 192, and 256 bits), benchmarking key generation time, throughput, key sizes, and operation latency. Our integration demonstrates transparent incorporation of these algorithms into TLS 1.3 and SSH protocols with 100% handshake success rates. Performance results indicate Kyber achieves 3-4× higher throughput (800-1150 ops/sec) and significantly smaller key sizes than Dilithium, with both offering similar security levels against quantum attacks. Furthermore, we provide an overall migration plan analysis, estimating an average implementation duration of 10.4 months per system type and total migration costs of approximately $724,122, in which databases require the largest amount of adjustment. Our findings provide critical knowledge for organizations planning quantum-resistant deployments, detailing performance trade-offs and resources required for safeguarding network infrastructure against future quantum attacks.