Before you invest any money, I think by far the smartest thing to do is download this trial of Traktor and just mess around with it with a keyboard and mouse. If it's something you enjoy, than upgrade! Otherwise you'll blow a bunch of money on midi controllers and soundcards only to discover it isn't something you don't really like.
Read it again. The 2.4GHz requirement is for an ancient Pentium 4 single core. You have a dual core (= a double CPU) so the speed requirements are lower. (You can't just compare clock frequencies because modern CPU's do a lot more the same number of clock cycles.)
See this CPU benchmarklist to see how the processors compare speedwise. It looks to me like a Pentium 4 2.4Hz must have a 3DMark06 CPU score (to pick just one) of around 700 (the 1.7GHz scores 620, and the 3GHz 811), while your Dual Core 2Ghz scores around 1551. That's twice as fast.
But, like I said elsewhere: make a request for a demo which is the complete program but time limited. The Pro 2 demo and full version of a previous version can be installed side by side, no problem. (But you can't run them at the same time.)
I have also only been DJing about a year. I'm running Traktor 2 Pro and the Stanton SCS.3 System. I started spinning in my warehouse for friends and a couple low key house parties. I'm now spinning art fairs, events, parties, and I was recently offered to spin a night at a real club. It really just comes down to practice, practice, practice.
Personally I use Traktor 2 Pro with a Numark Mixtrack and a NI Audio2.
Rock solid setup, and fits in a bag I can take anywhere with my laptop.
Whatever you do, with regards to at least the sound card, you need to make sure you have at least 2 independent outputs (Cue/Booth).
A Vestax Spin for $20?? Wow, provided it isn't broken, that's quite a bargain.
You can use the totally free Mixxx software, use the "home edition" of Virtual DJ, which is free too, or try out the Traktor Demo. (The latter plays for 30 minutes at a time after which the sound falls away, just restarting the program lets you repeat that, endlessly.) Traktor Pro currently costs less than $100, Virtual DJ is almost 3 times more expensive.
See, I've tried to get ALAC tagging support for Traktor 2 to work and my ALAC files converted from FLAC will not load nor is tagging supported.
ALAC or M4A files are not supported with Traktor 2.
See this link for verification:
http://www.native-instruments.com/en/products/dj/traktor-pro-2/specifications/?type=99
Now, this may have changed with the Traktor 2.5 update but as it stands now, Traktor nor Rekordbox support ALACS.
Let's see, a T5010 is apparently a 2-3 year old model with a Core Duo 2.4GHz, originally costing $1800 (!!!!). Ahum.
Do you like Virtual DJ, or would you prefer something else? I like Traktor, like a bunch of other people do too, apparently. You can request a demo on Native Instrument's website, and use it for a half hour before it blocks. Then you can restart Traktor, and repeat, indefinitely. That way you can safely test if your hardware is good enough.
If you like it, and you don't have copy of Traktor yet, you can rush and buy an S2. They're extra cheap ($399 on Amazon and on DJTT) until the end of next month. Really, it's a good quality controller (much better than most beginner controllers) and it comes with a full copy of Traktor Pro 2, which costs $199 on its own. Plus it includes a 4-channel (as mono, thus 2 x stereo) audio interface, which are not cheap either (> $100) if you have to buy one on its own.
Did you know that if you buy the X1 now, you get Pro 2 thrown in for free? Promotion till the end of September.
I would look at Traktor as far as software goes. You can get a free demo from http://www.native-instruments.com/en/products/dj/traktor-pro-2/demo-version/?r=4e1c4c61c6a5b
Once you play around with it using the keyboard and mouse, and you know you like this sort of stuff, go ahead and buy a controller. (I use Native Intruments Traktor Kontrol S4)
You can test Traktor Pro in chunks of 30 minutes, indefinitely. (After 30 minutes you have to quit and restart the program to continue)
I don't know if the same applies to Traktor 2, last time I looked there was no demo version available yet; but I wouldn't be too surprised if it did. It looks like it does...