Welcome to the non lurking side *:)
Short answer is yes you can use it. Longer answer is that it will limit the quality of the coffee you can produce with the Silvia over the next step up such as a Rocky, K3T etc.
In your spot make sure the Silvia is what you really want, the time taken from shot to steam and back is a pain considering you havnt had to wait with your last machines. Best thing is to go have a play with one at a sponsor if you can.
From there about the only other option in your budget is the Gee with a steam thermoblock like your Sunbeam but it runs a proper boiler for the brews.
Back to the grinder use your current one as a stop gap but start saving for a Christmas pressie for yoursselves *;)