Attitude...
...is worth a lot at entry level.
Took someone on who I felt was a better fit on the team in terms of personality, but other than tinkering at home he'd only ever worked as a shelf stacker. (He's 20 mind!)
I asked a few questions about current tech to gague his interest in it. If candidates know what a SAN is (just what it stands for, or what it's used for. Even "Storage" is a valid answer) then it suggest they at least try to keep up on development with enterprise tech. Someone who WANTS to learn is beter than someone who doesn't in my opinion.
A couple of years on a helldesk, hinting that you want to learn, do a self-taught A+ and Network+ and go in with the attitude that you're not experienced, but you're determined, want to learn and LOVE troubleshooting and customer service. That's what most people, IMHO would look for when getting a traniee / PFY in. If it's an entry level position a clean slate and desire to learn is the best I could ask for. The paperwork is just a useful deciding tool if stuck between a couple of candidates.
- PLAY! OSS is great, but I most companies don't want trainee staff around Linux boxes, and I'd wager there's less in use out in corporate world. Enjoy playing with every platform, but become a god on desktop Windows.
- A+ / Network+ are good, entry level bits of paper. But they show you know fundementals - nothing more. Self-study is cheap and will boost your credentials
- ESXi and Hyper-V are good freebie places to look at. Create a VM host and use the host to create test VM's for your learning machines!
- MS do free online virtual machines with training guides. They're actuall quite good. Imagine others provide something similar too.
- Enterprise versions of most software can be obtained via trial licences / eval copies from most big vendors.
- If you have a pro or ent version of Windows fire up gpedit.msc and play. I'd suggest in a VM if possible. Same with Windows firewall (advanced though).
- Keep ontop of industry news. El Reg, Neowin, The Inq and BBC Tech News are some of my favourites.
- Everyone needs platforms, web servers, databases, mail servers and directory services. Platforms are the starting point. Unless you want to be a DBA I suggest knowing different vendors, editions and maybe a play installing, but otherwise don't go in to deep. DBA is a job in itself and sits in IS rather than Infrastructure.
Most of all - enjoy it. Being enthuastic is your best bet. WIthout qualifications or experience behind you, you're going to need to sell yourself on your personality. I'd suggest going in as willing to learn and be shaped as possible, whilst showing your love for IT, customer service and desire to get into enterprise IT.
Good luck!