The Biblical evidence indicates that the disciples were saved on Resurrection Sunday, and that they received supernatural power when they were baptized with the Holy Spirit at Pentecost. These were two separate and distinct events with two separate and distinct purposes.
Now let's take a look at some more reasons why salvation and the baptism of the Holy Spirit are separate events:
Notice that after Jesus was baptized in water, the Holy Spirit descended on Him. Was this done to seal Jesus with the Holy Spirit as a guarantee of His salvation (as in Ephesians 1:13-14)? Obviously not, because Jesus was not in need of salvation. On earth, Jesus was our perfect role model because He was the perfect human, and He received the Holy Spirit in order to be empowered for His ministry on earth as the perfect human. This can be demonstrated by following the sequence of events in Luke's Gospel and in Acts:
"When all the people were being baptized, Jesus was baptized too. And as he was praying, heaven was opened and the Holy Spirit descended on him in bodily form like a dove." (Luke 3:21-22)
"You know what has happened throughout Judea, beginning in Galilee after the baptism that John preached-- how God anointed Jesus of Nazareth with the Holy Spirit and power, and how he went around doing good and healing all who were under the power of the devil, because God was with him." (Acts 10:37-38)
"Now Jesus himself was about thirty years old when he began his ministry." (Luke 3:23)
"Jesus, full of the Holy Spirit, returned from the Jordan and was led by the Spirit in the desert, where for forty days he was tempted by the devil." (Luke 4:1-2)
"When the devil had finished all this tempting, he left him until an opportune time. Jesus returned to Galilee in the power of the Spirit, and news about him spread through the whole countryside." (Luke 4:13-14)
First we are told that Jesus was baptized in water and then He received the Holy Spirit (not as a guarantee of His salvation, but for spiritual empowerment). We are also told that God anointed Jesus with the Holy Spirit and power. Next, Jesus began His ministry after receiving the Holy Spirit and power. We are then told that He allowed Himself to be led by the Spirit rather than deciding on His own what He wished to do. Finally, we see Jesus returning to Galilee in the power of the Holy Spirit after resisting the devil in the desert. So even though Jesus is the Son of God, the above passages tell us that He received the empowerment of the Holy Spirit for His earthly ministry. Notice that Jesus was already "saved" (because He was never "unsaved") when He received spiritual empowerment. So if we are to follow His example, don't we as we need to be saved before we can receive spiritual empowerment.